Bullet train service on JR East's northbound lines was suspended for two hours on Wednesday after smoke was seen coming from beneath a platform at Tokyo Station, the railway said.
East Japan Railway Co. resumed operations shortly past noon on the Tohoku, Joetsu, Nagano, Yamagata and Akita shinkansen lines after firefighters found no fire.
The railway said a station employee detected the smoke at around 9:50 a.m.
Operations on the Tokaido Shinkansen Line, operated by Central Japan Railway Co., were not affected by the incident.
The incident caused the cancelation of 20 train runs, and delays of up to two hours for 48 others, affecting about 33,000 passengers, JR East said.
The suspension caused Tokyo Station to become crowded with passengers.