A flow control device is capable of performing accurate flow control over a wide pressure range. The flow control device includes: a housing; a diaphragm splitting the housing into a gas chamber side to which gas is introduced and a fluid chamber side through which fluid passes, and being activated by the differential pressure generated between the gas chamber side and the fluid chamber side; and a valve body which operates in integration with the diaphragm to regulate the flow of the fluid introduced to the fluid chamber side. The diaphragm includes: a base part provided in a substantially central part of the diaphragm; and a thin film part provided on the outer rim of the base part. An opposing surface which is provided on the fluid chamber side to oppose the diaphragm includes a retaining form which retains the shape of the thin film part deformed by the differential pressure.