A gear coupling for a railway vehicle comprising: a first inner cylinder provided at a shaft end of a driving shaft, which is a rotating shaft of an electric motor, and including an external tooth gear; a first outer cylinder including an internal tooth gear meshing with the external tooth gear; a second inner cylinder provided at a shaft end of a driven shaft, which is a small gear shaft of a transmission gear, and including an external tooth gear; a second outer cylinder including an internal tooth gear meshing with the external tooth gear; a first closing plate interposed between the first inner cylinder and the second inner cylinder and closing an end face of the first outer cylinder in a direction in which the first outer cylinder and the second outer cylinder are opposed to each other; and a second closing plate interposed between the first inner cylinder and the second inner cylinder and closing an end face of the second outer cylinder in the direction, wherein in the first closing plate, one or a plurality of reversible through-holes communicating with a device outer side of the first closing plate from a first space surrounded by the first inner cylinder, the first outer cylinder, and the first closing plate are formed, in the second closing plate, one or a plurality of reversible through-holes communicating with a device outer side of the second closing plate from a second space surrounded by the second inner cylinder, the second outer cylinder, and the second closing plate are formed, characterised in that the gear coupling has a plugging member screwed into a surface on which the first closing plate and the second closing plate are opposed to each other and closing the through-holes is fitted to the through-holes formed in the first closing plate, a plugging member screwed into a surface on which the first closing plate and the second closing plate are opposed to each other and closing the through-holes is fitted to the through-holes formed in the second closing plate, a tip of a screw section of the plugging member fitted to the first closing plate is located on the first closing plate side with respect to a boundary between the first closing plate and the first space, and a tip of a screw section of the plugging member fitted to the second closing plate is located on the second closing plate side with respect to a boundary between the second closing plate and the second space. a first inner cylinder provided at a shaft end of a driving shaft, which is a rotating shaft of an electric motor, and including an external tooth gear; a first outer cylinder including an internal tooth gear meshing with the external tooth gear; a second inner cylinder provided at a shaft end of a driven shaft, which is a small gear shaft of a transmission gear, and including an external tooth gear; a second outer cylinder including an internal tooth gear meshing with the external tooth gear; a first closing plate interposed between the first inner cylinder and the second inner cylinder and closing an end face of the first outer cylinder in a direction in which the first outer cylinder and the second outer cylinder are opposed to each other; and a second closing plate interposed between the first inner cylinder and the second inner cylinder and closing an end face of the second outer cylinder in the direction, wherein in the first closing plate, one or a plurality of reversible through-holes communicating with a device outer side of the first closing plate from a first space surrounded by the first inner cylinder, the first outer cylinder, and the first closing plate are formed, in the second closing plate, one or a plurality of reversible through-holes communicating with a device outer side of the second closing plate from a second space surrounded by the second inner cylinder, the second outer cylinder, and the second closing plate are formed, characterised in that the gear coupling has a plugging member screwed into a surface on which the first closing plate and the second closing plate are opposed to each other and closing the through-holes is fitted to the through-holes formed in the first closing plate, a plugging member screwed into a surface on which the first closing plate and the second closing plate are opposed to each other and closing the through-holes is fitted to the through-holes formed in the second closing plate, a tip of a screw section of the plugging member fitted to the first closing plate is located on the first closing plate side with respect to a boundary between the first closing plate and the first space, and a tip of a screw section of the plugging member fitted to the second closing plate is located on the second closing plate side with respect to a boundary between the second closing plate and the second space.