Liquid supply apparatus

A liquid supply device (1) is disclosed, including: a liquid storage tank (2) which can pressurize the stored liquid; an injector-type pump (3) whose internal space (10) is formed by an injector (9) and a piston (11), the pressure of the liquid (L) is used to back the piston (11) off, the liquid is guided into the internal space (10) from the liquid storage tank (2), advance of the piston (11) can discharge the liquid (L) out from the internal space (11); a switching valve (6) which communicates the internal space (10) of the injector-type pump (3) with an inhalation flow path (5) for guidingthe liquid (L) into the internal space (10) from the liquid storage tank (2) or with a discharging flow path (8) for discharging the liquid (L) to outside; a driving mechanism (4) which includes a pushing component (14), the pushing component can move towards the advancing direction and backing direction of the piston (11), and can lean against outer side of the piston (11) to advance the pistol (11); a sensor (15) which