A freighter train derailed early Sunday on the JR Esashi Line in southern Hokkaido, the operator said. No one was injured.
JR Hokkaido said the last two cars of the 20-car train came off the rails at around 4:15 a.m. on a section of the Esashi Line between Izumisawa and Satsukari stations. The cause is being probed with the assistance of the transport ministry's railway accident investigators.
The freighter train was being operated by a 31-year-old driver, JR Hokkaido said.
The driver was quoted as saying that he noticed the derailment only after the emergency braking system was activated. When he got off the stationary train and checked for any problems, he found the wheels of the last two cars were about 50 cm off the tracks.
In recent months, JR Hokkaido has seen several derailments, raising suspicions that the accidents may be due to the company's systemic safety shortcomings.
"We deeply apologize for causing anxiety to the public," JR Hokkaido President Fumihisa Nishino told a news conference in Sapporo. He said the section of track where Sunday's mishap occurred was checked as recently as June 4.
No irregularities were found when the cars that came off the tracks were checked on April 28, the operator said.
The Esashi Line is close to Hakodate and part of the route linking Honshu and Hokkaido via the Seikan undersea tunnel. Due to the derailment, train services linking the two islands were suspended.