National Diet Building

The National Diet Building is the center of Japan's legislature, located a 3-minute walk from Tokyo Metro's Nagatacho Station. Construction began in 1920 and was completed in 1936. The building features the House of Representatives on the left and the House of Councillors on the right, separated by a central tower. The interior is a majestic representation of traditional Japanese architecture and is open for tours on weekdays. While reservations are required for the House of Councillors, the House of Representatives does not require a reservation for visits. The tour lasts about an hour and includes the main chamber, the central hall, and the resting room. In autumn, the ginkgo trees lining the area turn a beautiful color, making it a popular spot for visitors.

Basic Information

Spot Name
National Diet Building
Location
〒100-0014 1-7-1 Nagatacho, Chiyoda-ku, Tokyo 
Access
3-minute walk from Exit 1 of the Subway "Kokkai-gijidōmae" Station
3-minute walk from Exit 1 of the Subway "Nagatacho" Station
Parking
Please use the nearby paid parking.
Business Hours
House of Representatives: 8:00 AM - 5:00 PM (last admission at 4:00 PM), Saturday, Sunday, and holidays at 9:30 AM, 10:30 AM, 11:30 AM, 1:00 PM, 2:00 PM, and 3:00 PM
House of Councillors: 9:00 AM - 4:00 PM (every hour on the hour)
*On days when a plenary session is held, visits are not allowed from one hour before the scheduled start time until the session is adjourned.
Regular Holiday
It varies between the House of Representatives and the House of Councillors.
Fees
Free
Contact Information
Phone Number:03-5521-7445
Official Website

Map

Detailed Information

The National Diet Building is the facility that houses the National Diet of Japan, the center of the nation's political system, located in Nagatacho, Chiyoda, Tokyo. It is about a three-minute walk from the Tokyo Metro “Kokkai-gijidō-mae Station” and serves as the venue for the bicameral legislature, consisting of the House of Representatives and the House of Councillors. Important proceedings related to national governance, such as the enactment of laws, budget approval, and the appointment of the Prime Minister, take place here.

**History and Construction Background**
The first Imperial Diet was held in 1890, but the first temporary Diet building was destroyed by fire just two months later. The second temporary Diet building was also lost to a fire, leading to the construction of a third temporary Diet building.

The current National Diet Building was constructed based on a design selected through a public competition held in 1920. The construction plans were undertaken by Watanabe Fukuzō, an engineer from the Ministry of Home Affairs, and construction began. However, due to issues related to the loss of the temporary building, work was temporarily halted, and the building was finally completed in 1936, 17 years after construction began.

**Building Overview**
The National Diet Building is made of steel-reinforced concrete, standing three stories above ground (with the central tower rising to four stories) and one story below. The entire building is approximately 206 meters long and 89 meters deep, with the central tower reaching about 65 meters in height. About 30,000 tons of granite and marble from across the country were used in its construction, involving a total of approximately 2.54 million people.

The structure is symmetrical, with the House of Representatives on the left side and the House of Councillors on the right side when viewed from the front.

**Visiting Information**
The National Diet Building can be visited by reservation. Both the House of Representatives and the House of Councillors can be toured for free, taking approximately one hour. Guided tours are provided by staff along a designated route.

**House of Councillors Tour Route**
- Observation Lobby (exhibits of the Speaker's gavel replica, Emperor's chair, etc.)
- Main Assembly Hall
- Emperors' Rest Room
- Central Hall
- Front Garden

**House of Representatives Tour Route**
- Main Assembly Hall
- Emperors' Rest Room
- Noblemen's Room
- Central Hall
- Front Garden

There is also a shop that sells original goods exclusive to the National Diet Building, including sweets and clear files with illustrations of past Prime Ministers.

**Central Hall and Architectural Beauty**
The Central Hall is located directly beneath the tallest central tower of the building, with a ceiling height of about 33 meters. Statues of notable figures who contributed to Japanese parliamentary politics, such as Ito Hirobumi (first Prime Minister), Okuma Shigenobu (founder of Waseda University and former Prime Minister), and Itagaki Taisuke (a pioneer of the civil liberties movement) are placed here. The fourth pedestal, which remains without a statue, symbolizes the idea that "there is no conclusion in politics" and has many associated anecdotes.

The floor of the hall is adorned with around one million mosaics using over ten types of marble. Okinawa coral limestone is used in the columns and walls, which are characterized by visible fossilized shells. Oil paintings depicting Japan's four seasons are displayed in each corner.

**The Opulent Decoration of the Emperors' Rest Room**
The "Emperors' Rest Room," where the Emperor rests during the opening ceremonies, is the most luxurious room in the National Diet Building. The interior features Japanese traditional crafts, including hinoki wood, lacquer, gold leaf, and raden (a decorative technique using shell). It is said that Mount Fuji was once visible from this room, although it can no longer be seen due to surrounding buildings.

**Structure of the Assembly Hall**
The assembly hall, where main sessions are held, is located on the second floor and features an atrium structure. The ceiling has stained glass skylights beautifully decorated with arabesque patterns. The seats are arranged in a semi-circular shape, with 460 seats allocated in the House of Representatives. This number is greater than the current number of members, anticipating future increases.

Acoustic design is also carefully considered, utilizing wood and silk fabric to minimize echoes.

**Front Garden and Lighting**
In the front garden of the National Diet Building, trees donated from all over the country commemorate the 80th anniversary of the Diet's establishment in 1970. A fountain was also installed to celebrate the 100th anniversary in 1990.

In mid-November, the approximately 300-meter-long row of ginkgo trees at the front of the building turns golden, making it a beautiful autumn spot known as the "Golden Road."

Furthermore, in celebration of the 100th anniversary of the Diet's establishment, the central tower has been illuminated from sunset until 8 PM during the regular Diet session since November 1990, creating a magical atmosphere around the National Diet Building at night.