<p>Provided is a diaphragm valve which prevents large scratches from being inflicted on the valve body, even if seat replacement is carried out repeatedly. The diaphragm valve comprises: a body (2); a seat (4) which is detachably positioned on the rim of a fluid passage (2a) formed on the body (2); and a seat holder (5) that is positioned detachably with respect to the body (2) and which holds the seat (4). The body (2) and the seat holder (5) are both made from metal. The Vickers hardness of the seat holder (5) is lower than the Vickers hardness of the body (2).</p>
