To provide an electric power-assisted steering device capable of providing a driver with steering auxiliary force.

This electric power-assisted steering device includes: a steering torque sensor 110 for detecting steering torque acting on a steering wheel to output a steering torque signal; a vehicle speed sensor 111 for detecting a vehicle speed to output a vehicle speed signal; a steering auxiliary force setting section for outputting a signal representing linear change gradually increasing or decreasing based on the operation of a driver; a map setting section 112a for setting a steering auxiliary force map by gradually increasing or decreasing a ratio of a target motor current to maximum steering torque, a maximum target motor current or steering torque at a specific speed by receiving input of the signal output from the steering auxiliary force setting part; a current signal supply section 112c for outputting a target motor current signal applicable to the steering torque signal and the vehicle speed signal in accordance with the steering auxiliary force map; and a motor drive section 113 for supplying a current corresponding to the target motor current signal to a motor 108.