The National Museum of Modern Art

3-1 Kitanomaru-koen, Chiyoda-ku, Tokyo 102-8322
3 minutes from Takebashi station (Subway Tozai Line)
Site: The National Museum of Modern Art

The permanent exhibition consists of paintings, sculptures, prints, watercolors, drawings, photographs, and other works dating roughly from the beginning of the 20th century to the present and provides an overview of the history of modern art.
I recommend you to also visit the museum shop, there you can find very nice and cheap reprodactons (around 300 Yen) of some of the painings that displayed in the museum.
Opening Hours:
10:00 - 17:00 (Admission until 16:30),
Friday until 20:00 (Admission until 19:30)
Closed: Mondays (open on holiday Mondays and close on the following days), December 29 – January 1
Admission:
Adults ¥420
College Students ¥130
High School Students ¥70
Children under 15 and Senior over 65 free
Free on May 18, November 3 and on the first Sunday of each month