A solenoid valve for controlling a flow rate of working fluid flowing in a valve passage according to an electromagnetic force, comprising: a main poppet configured to control the flow rate of the working fluid flowing in the valve passage by moving according to a pilot pressure; an auxiliary poppet configured to adjust the pilot pressure by moving according to the electromagnetic force; and annular first and second seat portions provided in the valve passage; wherein: the main poppet includes a poppet valve configured to close the first seat portion by being seated on the first seat portion and a spool valve slidably provided in the inner periphery of the second seat portion; the spool valve includes an outer peripheral surface slidable relative to an inner peripheral surface of the second seat portion and a throttle portion open on the outer peripheral surface and configured such that an area thereof exposed from the second seat portion changes in accordance with a movement of the spool valve; the first seat portion is provided downstream of the second seat portion; the spool valve includes an annular portion slidably provided in the inner periphery of the second seat portion; the solenoid valve being characterized in that the throttle portion is a through hole provided in the annular portion and allowing communication between an inner periphery and the outer periphery of the annular portion. a main poppet configured to control the flow rate of the working fluid flowing in the valve passage by moving according to a pilot pressure; an auxiliary poppet configured to adjust the pilot pressure by moving according to the electromagnetic force; and annular first and second seat portions provided in the valve passage; wherein: the main poppet includes a poppet valve configured to close the first seat portion by being seated on the first seat portion and a spool valve slidably provided in the inner periphery of the second seat portion; the spool valve includes an outer peripheral surface slidable relative to an inner peripheral surface of the second seat portion and a throttle portion open on the outer peripheral surface and configured such that an area thereof exposed from the second seat portion changes in accordance with a movement of the spool valve; the first seat portion is provided downstream of the second seat portion; the spool valve includes an annular portion slidably provided in the inner periphery of the second seat portion; the solenoid valve being characterized in that the throttle portion is a through hole provided in the annular portion and allowing communication between an inner periphery and the outer periphery of the annular portion. the main poppet includes a poppet valve configured to close the first seat portion by being seated on the first seat portion and a spool valve slidably provided in the inner periphery of the second seat portion; the spool valve includes an outer peripheral surface slidable relative to an inner peripheral surface of the second seat portion and a throttle portion open on the outer peripheral surface and configured such that an area thereof exposed from the second seat portion changes in accordance with a movement of the spool valve; the first seat portion is provided downstream of the second seat portion; the spool valve includes an annular portion slidably provided in the inner periphery of the second seat portion; the solenoid valve being characterized in that the throttle portion is a through hole provided in the annular portion and allowing communication between an inner periphery and the outer periphery of the annular portion.