Control device, control method and electric motor car

A control device for an electric motor car comprising: a switch which is installed between a power supply source and a power line drawn through the electric motor car; a battery which supplies power to a main motor of the electric motor car; a step-up unit, which is installed between the power line and the battery, configured to increase a voltage; and a control unit which breaks a connection between the power supply source and the power line using the switch when braking the electric motor car, increases the power supplied from the battery using the step-up unit, and performs regenerative braking in the main motor to which the increased power is supplied.