To structurally prevent an excessive load from being applied to the expansion of a bearing at heat generation by supporting the bearing elastically with regard to the seizure prevention of a bearing in a gear device accompanying the high-speed rotation of an electric motor for vehicles.

The outside diameter of a cylinder A, which has a flange at one end and whose inside diameter part has a penetrating structure, is used as an inlay part between the cylinder and a gear box. A cylinder B, one end of which is closed by a disk, is structured in the inside diameter part of the cylinder A by allowing the shaft centers of both cylinders to match in such a way that the disk comes close to the flange. By combining the flange part of the cylinder A and the disk part of the cylinder B at each outside circumferential part and by supporting the bearing by the inside circumferential part of the cylinder B, a taper roller bearing of the gear device is elastically supported in the axial direction. With the achievement of the seizure preventing structure of the bearing, an oil amount and a bearing gap can be reduced, thereby contributing to countermeasures against oil leak from labyrinth, noise, and damage to the retainer of the bearing.