A cooling circuit for an electric motor for a construction machine includes a circulation line that includes a shaft-side line disposed in a rotor shaft of the electric motor, a pump that supplies cooling fluid to the circulation line, a first filter disposed between the pump and the shaft-side line in the circulation line, a first bypass line that bypasses the first filter so as to connect an upstream side and a downstream side of the first filter, and a first relief valve disposed in the first bypass line.