Abstract: This invention provides a heat transmitting pipe and a heat transmitting plate which are capable of greatly improving the heat transfer efficiency of a conventional finned heating pipe and a convention heating plate. Copper oxide powder is deposited in a vapor phase onto a cellular synthetic resin coated with an adhesive beforehand. Thereafter, a copper plate with the same metal powder deposited thereon is placed on one surface of the metal powder-bearing cellular synthetic resin and is brought into lightly pressed contact with the surface by a roll press or the like, to thereby form a laminated article. Subsequently, the cellular synthetic resin is burnt off in a combustion furnace, to thereby produce a cellular metal material of the copper oxide on the copper plate. Further, the cellular metal material is reduced and sintered in a reducing atmosphere such as that of a hydrogen reduction furnace, to thereby produce a cellular copper material which is provided with the copper plate on one surface thereof.