PURPOSE: To produce a homogenous sintered body with a high density through a hot hydrostatic press of sintering powder packed and sealed into an exhaust pipe following a deairing of a vessel filled with the powder by a deairing pipe provided thereon.

CONSTITUTION: A vessel 1 having a cover 2 with a deairing pipe 2' is filled with powdery material 10. The vessel is deaired with an exhaust pipe 3 having a bypass pipe attached to a deairing pipe 2. At the same time, powder 10' of the same kind as the powdery material 10 is placed between valves 6 and 7 mounted to the bypass pipe 4 and the valve 6 is opened and the valve 7 closed. After a deairing of the bypass pipe 4, the valve 6 is closed and the valve 7 opened, the powder is fed down into the deairing pipe 2. Thereafter, the deairing pipe 2' is closed tight and the powder 10' is sealed into a convex space formed on a cover 2. It is subjected to pressurization and sintering by a hot hydrostatic press method. In this manner, a homogenous sintered dody with a high density can be produced without any pore.