Manually-operated diaphragm valve

Provided is a manually-operated diaphragm valve that can set the open/close range of a valve body while maintaining compactness with a simple structure, that can ensure a sufficient flow rate during a fully-opened period without being affected by individual differences of the internal shape of the valve, and that can optionally adjust the flow rate during the fully-opened period. A valve body 1 is provided with a valving element 12 that is mounted inside of a body 10, and a spindle 13 that is screw-fastened to the body 10 in a vertically movable manner so as to cause the valving element 12 to come close to or separate from a valve seat 14. To the upper portion of the valve body 1, a handle 2 is attached so as to manually rotate the spindle 13. In the vicinity of a portion above the valve body 1, a fully-opened position adjustment mechanism 20 is provided which regulates rotational movement of the handle 2 on the valve-opening operation side during the fully-opened period and which sets the upper limit of the