A diaphragm valve including: a valve body having a flow path formed therein and a valve chamber recessed from an upper surface of the valve body; a diaphragm that is disposed in the valve chamber and elastically deformable to open and close the flow path and adjust an opening degree of the flow path; a stem for pressing the diaphragm to elastically deform the diaphragm; an actuator for driving the stem; a support mechanism that is fixed to the valve body and supports the stem and the actuator; wherein the stem includes a first stem member connected to the actuator via a displacement transmitting member, and a second stem member held by the support mechanism so as to be movable in the axial direction via a sleeve, the second stem member has an upper end portion which abuts against a lower end portion of the first stem member.