The present invention relates to a porous lightweight iron and a method for preparing the same, and more particularly to a porous lightweight iron having decreased weight due to pores formed therein while having a strength similar to that of existing steel products; and a method for preparing a porous lightweight iron having desired properties or various properties according to intended use. As described above in detail, according to the present invention, the thickness, weight and strength of lightweight iron to be produced, can be controlled, thus making it possible to prepare porous lightweight iron having desired properties by controlling the sintering temperature during the preparation process, the mixing ratio of diamond or silicon carbide and the mixing ratio of raw materials. Also, since the porous lightweight iron prepared according to the present invention has a weight per unit volume of 10 to 65% (W/V), compared to the existing iron steel products, it is possible to increase economic efficiency and improve processing convenience, when applied to an actual industry.