A steering system to steer wheels by a movement of a steering shaft, including: the steering shaft; an electric motor; a converter configured to convert a rotational motion of the motor into the movement of the steering shaft; a motor rotation angle obtainer configured to obtain a motor rotation angle from a zero point position; a movement-amount-related-amount obtainer configured to obtain a movement-amount-related amount that is a movement amount of the steering shaft from a neutral position or a physical amount in a one-to-one correspondence with the movement amount; and a controller including a malfunction detector configured to detect a presence or absence of a malfunction of the converter in a mode that differs depending on a temperature state of the steering system, based on the motor rotation angle from the zero point position obtained by the motor rotation angle obtainer and the movement-amount-related amount obtained by the movement-amount-related-amount obtainer.