An electric motor system includes an electric motor, an electric brake, a power line, and a driver. The electric brake is integrated with the electric motor and configured to generate braking force against the drive force. The driver is integrated with the electric motor and the electric brake. The power line connects the electric brake to an electric power source via the driver to supply electric power to the electric brake. The driver includes a first circuit and a conduction bypath. The first circuit connects the electric brake to the power source such that electric power is supplied to the electric brake and disconnects the electric brake from the electric power source. Electric power is to be supplied to the electric brake from the electric power source through the conduction bypath even when the first circuit disconnects the electric brake from the electric power source.