A heating cooker comprising: a heating chamber for accommodating an object to be heated therein; multiple pairs of supports formed on or with opposite side walls of the heating chamber to support a tray on which the object to be heated is placed; a water storage tank which stores water therein that is used to generate steam; a steam generating unit provided with a steam heating heater; a water pump which sends the water in the water storage tank to the steam generating unit through a water-supply pipe conduit; a steam outlet formed in a wall of the heating chamber, so that the steam generated by the steam generating unit is ejected into the heating chamber through the steam outlet and blown onto the object to be heated; a control unit operable to control the steam generating unit; wherein the steam outlet is positioned on an upper side of uppermost supports, and the control unit energizes the steam heating heater from the start of cooking to supply steam generated by the steam generating unit to the heating chamber through the steam outlet to thereby heat the object to be heated with the steam; characterized in that: the steam outlet is formed in one of the side walls of the heating chamber; a tubular grill heater is mounted on an upper surface of the heating chamber to heat the objet to be heated from above by radiant heat; the control unit is operable to control the grill heater, and simultaneously energizes the steam heating heater and the grill heater from the start of cooking, and a surface of the object to be heated is simultaneously grilled or roasted by radiant heat from the grill heater; wherein the control unit controls the amount of energization of the steam generating unit so as to be greater than the amount of energization of the grill heater for a predetermined period of time from the start of cooking and also controls, after a lapse of the predetermined period of time, the amount of energization of the grill heater so as to be greater than the amount of energization of the steam generating unit. a heating chamber for accommodating an object to be heated therein; multiple pairs of supports formed on or with opposite side walls of the heating chamber to support a tray on which the object to be heated is placed; a water storage tank which stores water therein that is used to generate steam; a steam generating unit provided with a steam heating heater; a water pump which sends the water in the water storage tank to the steam generating unit through a water-supply pipe conduit; a steam outlet formed in a wall of the heating chamber, so that the steam generated by the steam generating unit is ejected into the heating chamber through the steam outlet and blown onto the object to be heated; a control unit operable to control the steam generating unit; wherein the steam outlet is positioned on an upper side of uppermost supports, and the control unit energizes the steam heating heater from the start of cooking to supply steam generated by the steam generating unit to the heating chamber through the steam outlet to thereby heat the object to be heated with the steam; characterized in that: the steam outlet is formed in one of the side walls of the heating chamber; a tubular grill heater is mounted on an upper surface of the heating chamber to heat the objet to be heated from above by radiant heat; the control unit is operable to control the grill heater, and simultaneously energizes the steam heating heater and the grill heater from the start of cooking, and a surface of the object to be heated is simultaneously grilled or roasted by radiant heat from the grill heater; wherein the control unit controls the amount of energization of the steam generating unit so as to be greater than the amount of energization of the grill heater for a predetermined period of time from the start of cooking and also controls, after a lapse of the predetermined period of time, the amount of energization of the grill heater so as to be greater than the amount of energization of the steam generating unit. the steam outlet is formed in one of the side walls of the heating chamber; a tubular grill heater is mounted on an upper surface of the heating chamber to heat the objet to be heated from above by radiant heat; the control unit is operable to control the grill heater, and simultaneously energizes the steam heating heater and the grill heater from the start of cooking, and a surface of the object to be heated is simultaneously grilled or roasted by radiant heat from the grill heater; wherein the control unit controls the amount of energization of the steam generating unit so as to be greater than the amount of energization of the grill heater for a predetermined period of time from the start of cooking and also controls, after a lapse of the predetermined period of time, the amount of energization of the grill heater so as to be greater than the amount of energization of the steam generating unit.