A current controller includes a current control circuit and a current detection circuit, which detects a current flowing through a solenoid of an electromagnetic proportional relief valve. The current control circuit sets a current command to a sum of a value obtained by multiplying a feedforward gain by a target current value, a value obtained by multiplying a proportional gain by a current deviation, and a value obtained by multiplying an integral gain by a current deviation integral value. The current control circuit then controls the current flowing through the solenoid in accordance with the current command. When the current detected by the current detection circuit is less than or equal to the predetermined value, the current control circuit resets the current deviation and the current deviation integral value and sets the current command based on the reset values.