The present invention provides a separator that, when used in a lithium ion secondary battery, polymer lithium secondary battery, aluminum electrolytic capacitor or electric double-layer capacitor, offers desired levels of various practical characteristics, undergoes minimal heat shrinkage even when overheated, and exhibits high reliability and excellent workability. The electronic component separator proposed by the present invention comprises a porous base made of a substance having a melting point of 180° C. or above, and a resin structure provided on at least one side of and / or inside the porous base, and the porous base and / or resin structure contains filler grains.