A crystalline polymer microporous membrane, which contains: a laminate of two or more layers including a layer containing a first crystalline polymer and a layer containing a second crystalline polymer, the laminate having a plurality of pores each piercing through the laminate in a thickness direction thereof, wherein the first crystalline polymer has higher crystallinity than crystallinity of the second crystalline polymer, and the layer containing the first crystalline polymer has the maximum thickness thicker than the maximum thickness of the layer containing the second crystalline polymer, and wherein at least one layer in the laminate has a plurality of pores whose average diameter continuously or discontinuously changes along with a thickness direction of the laminate at least at part thereof.