PURPOSE: To provide a hot chamber having excellent durability by constituting said chamber of the ferrous sintered material dispersed and incorporated with hard particles at an adequate area ratio by diffusing and solutionizing the periphery thereof partially into matrix and ferrous sintered material having good heat conductivity.

CONSTITUTION: The 1st member including the part to contact slidingly with the valve on a combustion side of the hot chamber for an internal-combustion engine consists of the ferrous sintered material which contains the hard particles having≥500 Hv at 3W30% area ratio and in which the components of such hard particles are dispersed by partially diffusing and solutionizing the same at the periphery of the particles into the matrix consisting mainly of pearlite. The 2nd member corresponding to the cylinder head except the above consists of the ferrous sintered material having at least ≥0.01Cal/cm.sec.°C heat conduc tivity and having the heat conductivity equal to or higher than the heat conduc tivity of the above-mentioned 1st member. The above-mentioned 1st member consists preferably of 0.8W35wt% C, 1.0W10.0% Cr, 0.2W6.0% Ni, 1.0W10.0% Mo, 1.0W15.0% Co and the balance substantially Fe and the 2nd member consists of 0.8W3.0% C, 0.5W5.0% Cr, 1.0W5.0% Cu and the balance Fe.