Tokyo DisneySea in Urayasu, Chiba Prefecture, closed four hours early at 6 p.m. Friday due to a major power outage that began at around 3:30 p.m., theme park operator Oriental Land Co. said.
The company said it had not yet decided whether to open Saturday.
There were no injuries reported, and about 16,000 visitors in the amusement park remained calm as lights inside shops and on streets in the park stayed on despite the power failure, which affected seven of the 23 attractions, the company said.
Visitors were given the option of moving to the adjacent Tokyo Disneyland.
Tokyo DisneySea also refunded people's passes and gave out discount coupons for future visits.
The company said the blackout was apparently caused by trouble at its electric transformer station.
This is the first time that either Tokyo DisneySea, which opened in September 2001, or Tokyo Disneyland, which opened in April 1983, has suspended operations due to a blackout.