Provided is a porous body, which is formed of a resin obtained by crosslinking a copolymer of ethylene, an α-olefin, and a non-conjugated diene, wherein porosity of the porous body is in the range of 50 to 95% by volume, strength of the porous body at 50% compression is 300 kPa or less, and compression set (A) under atmosphere at a temperature of 80°C and a relative humidity of 90% is 20% or less.