A chassis dynamometer for a vehicle has a base seat, a fixed shaft having one end thereof attached to the base seat, a rotary proximal portion rotatably supported to the fixed shaft, a roller connected to the rotary proximal portion, for loading a wheel of a vehicle, and a motor connected to the roller so that power can be transmitted therebetween. The roller has a single flange portion connected to the rotary proximal portion and extending obliquely to the axis, and an outer peripheral portion extending both axial directions from an outer periphery of the flange portion and disposed outward in the radial direction of the motor.