PURPOSE: To improve operability by a method wherein respective rails are provided with extensions to construct sidetracks in a rolling stock maintenance device, provided with the trolley rails and swing-preventing rails arranged in rectangular shapes and effecting service works or the like by hanging the rolling stocks by trolleys.

CONSTITUTION: The deviation preventing rails 2, arranged in rectangular shapes at both sides immediately below the trolley rails 1 arranged in rectangular shapes in the rolling stock service device, are constructed and a self-propelling motor trolleys 4, having rolling stock hanging device 3, are moved on the trolley rails 1. The trolley rails 1a and the rolling stock deviation preventing rails 2a are extended to arbitrary directions at cornering places A, B while a part 2b of the rail 2a are constituted so as to be free of opening and closing and, thus, the side-tranks are constructed. Turning rails 5 are provided at the cornering places. According to this method, in case the rolling stock, waiting for a service part therefor, is generated upon effecting the service works, the trolley 4, carrying this rolling stock, is received and waited in any sidetrack, while other rolling stocks may continue the service works therefor.