A crystalline polymer microporous membrane, which contains a laminate containing two or more layers and a plurality of pores piercing through the laminate in a thickness direction thereof, where the two or more layers include a layer containing a first crystalline polymer, and a layer containing a second crystalline polymer stacked to form the laminate, wherein the first crystalline polymer has a higher melting point than a melting point of the second crystalline polymer, wherein at least the layer containing the second crystalline polymer in the laminate has a microstructure containing at least fibrils having an average long axial length of 1 μm or shorter, and wherein at least one of the layers constituting the laminate has a plurality of pores whose average pore diameter is constant without any variation at least at part along a thickness direction of the laminate.