The transport ministry began inspecting East Japan Railway Co. Tuesday morning in a rare move that follows a series of service disruptions due to human error.
The ministry also said it will consider administrative penalties.
According to the Land, Infrastructure and Transport Ministry's Railway Bureau, it is the first time on-site inspections have been conducted of the JR group as a result of a specific accident or problem.
On Sept. 28, train services on the JR Chuo Line in Tokyo were suspended for eight hours between Mitaka and Tachikawa stations due to delays in overnight construction work caused by various problems, including faulty wiring of signal equipment.
The ministry is expected to have JR East submit construction plans and contracts with the construction firms and question staff. It may also inspect JR's safety management system, including what instructions it gave the firms and what checks were done during the construction.
The ministry will consider imposing administrative penalties after inspecting nine departments at JR East over three days starting Tuesday.
In an accident on Oct. 6, a power shovel scoop left on the tracks of the JR Keihin Tohoku Line in Tokyo's Shinagawa Ward was hit by a train, halting services for four hours during morning rush hour.
The law on railway services stipulates that when deemed necessary by the transport minister, the ministry can inspect offices, facilities and records of railways and question officials. Except for regular inspections, it is rare for the ministry to look into specific problems.