To provide a diaphragm valve having a small number of parts for assembly, facilitating connection of a stem, a compressor and a diaphragm, and having excellent cut-off performance as a valve.

In this diaphragm valve, the diaphragm 2 is provided with an embedded fitting 3 projected in T-shape onto the noncontact liquid surface side, and the lower part of the stem is provided with a stem tip part of circular outer shape partially cut out to be fitted and positioned to the compressor 4 and having a T-shaped groove 5a1 inside to fit a T-shaped projecting part 3a of the embedded fitting. The center part of the compressor is provided with a stem fitting recessed part 4a of a circular hole with the circumference partially projected in the center direction.