This apparatus for manufacturing a semiconductor single crystal includes: a crucible; a heater; a crucible driving unit; a chamber for housing the crucible and the heater; and a hydrogen mixed gas supplying device for supplying into the chamber a hydrogen mixed gas including an inert gas in admixture with a hydrogen-containing gas that contains hydrogen atoms, wherein the hydrogen mixed gas supplying device includes: a hydrogen-containing gas supply unit; an inert gas supply unit; a hydrogen-containing gas flow rate controller; an inert gas flow rate controller; and a gas mixing unit for uniformly mixing together the hydrogen-containing gas and the inert gas so as to form a hydrogen mixed gas.