A hollow poppet valve (10) is provided with an additional flange shape cavity (S1a), in addition to an ordinary valve head cavity (S1) formed in the valve head (14) of the valve (10) in communication with a valve stem cavity (S2) formed in a valve stem (12). A coolant (19) is loaded in the cavities to facilitate dissipation of heat out of the valve. This flange shape cavity (S1a) extends radially outwardly round a bottom portion of the valve head cavity (S1), extending close to a valve seat, thereby significantly facilitating heat transfer between the coolant (19) and the valve seat of the valve, yet, since the flange shape cavity (S1a) does not influences the thickness of other regions of the valve, it does not degrade durability of the valve.