Lotus-type porous iron and stainless steel (SUS304L) whose long cylindrical pores are aligned in one direction were fabricated by unidirectional solidification in a pressurized hydrogen or nitrogen gas atmosphere. Pores are formed as a result of precipitation from the supersaturated gases when the liquid metal dissolved with gas atoms is solidified. The ultimate tensile and yield strengths of the porous iron produced in nitrogen atmosphere are about two times higher than in a hydrogen atmosphere. Such superior strength is attributed to solid-solution hardening due to solute nitrogen atoms in iron matrix.