An infrared heater includes a support body and a heat source irradiating device. The heat source irradiating device includes a reflecting hood, a hood body, two non-planar symmetric arc bodies disposed on the top surface of an n-shape body, a casing, and an infrared tube, such that a radiant heat at the upper half of the infrared tube can be radiated from an open end having an included angle from 60° to 80° from the hood body after the radiant heat is reflected from the two arc bodies. Its radiant heat can avoid the infrared tube during its reflection to improve the heat reflecting efficiency, extend the life expectancy of the infrared tube, and enhance the irradiating range of the heater and the evenness of heat energy.