PURPOSE: To lower the combusting noise of an infrared-ray combusting apparatus using a gas fuel and to obtain uniform intensity of combustion, by designing a flame board made of a heat-resisting porous plate such that round flame holes having a large diameter and those having a small diameter are formed alternately at the lower portion of the flame board.

CONSTITUTION: Gas fuel supplied from a gas supply pipe 3 is injected into an inner space formed inside a flame board 1 from a gas injecting port 4 and ignited by an igniting means (not shown). On the other hand, air necessary for combustion is supplied from round holes 2aW2c formed in the flame board 1. Therefore, flame is formed just at the positions of these flame holes 2aW2c. At the same time, flame board 1 is red-heated and infrared rays are radiated through a heat transmitting member 6 attached to an outer case 5 which is placed with proper spacing from flame board 1. Here, arrangement is such that round flame holes 2b having a large diameter and those 2c having a small diameter are disposed alternately at the lower portion of flame board 1, so as to prevent excessive supply of air and to render the intensity of combustion uniform over the entire surface of the flame board.