An apparatus for generating high temperature steam according to the present invention comprises a high pressure container including a hollow body having a certain volume and sealed shape and a vapor outlet formed at an upper or lower portion of the body for discharging vapor generated therein; a heat supply unit for supplying high temperature heat to the high pressure container; a water supply pump positioned at an outside of the high pressure container and supplying the high pressure container with water from an outside; a spray nozzle for spraying the water supplied from the water supply pump to the high pressure container; and a vapor discharge line connected to the outlet of the high pressure container to guide the vapor generated in the body.