A plurality of porous metal bodies which are bonded with each other at bonded-boundary surfaces parallel to a first direction, each of the porous metal bodies has a three-dimensional network structure formed from a continuous skeleton in which a plurality of pores are interconnected so as to have a porosity rate different from another porous metal body, the pores formed in at least the porous metal body having the higher porosity rate are formed to have flat shapes which are long along a direction parallel to the bonded-boundary surface and short along a direction orthogonal to the bonded-boundary surface, an entire porosity rate of a bonded body of the porous metal bodies is 50% to 92%, a compressive strength compressing in the direction parallel to the bonded-boundary surface is 1.4 times to 5 times of a compressive strength compressing in the direction orthogonal to the bonded-boundary surface.
