PURPOSE: To improve the producing rate and the quality in a porous metal wire by using an ingot obtd. by subjecting a mixture of metal obtd. by imparting viscosity to molten metal and thereafter powdering it and a foaming agent to heating and sintering at a specified temp. as a wire rod and subjecting it to heating and foaming at a specified temp.

CONSTITUTION: By a method in which oxides such as Al2O3 and MgO are mixed in molten metal or the molten metal is stirred and is positively brought into reaction with the air, the molten metal is oxidized, and the metal is imparted with sufficient viscosity. This metal having viscosity is powdered by an atomizing method. This metal powder is uniformly mixed with a foaming agent, which is formed and is thereafter subjected to heating and sintering at a temp. of the foaming starting temp. of the foaming agent or below into an ingot. This ingot is subjected to extrusion into a metal wire and is heated at a temp. of the foaming starting temp. of the foaming agent or above, by which the foaming agent is foamed at a prescribed foaming degree. By changing the amt. of the foaming agent, the foaming temp. and the heating time, the foaming degree can optionally be controlled.