A separator for a lead-acid battery, a pasting paper for a lead-acid battery, a plate for a lead-acid battery, and a lead-acid battery using the same are disclosed. The separator comprises a microporous sheet containing a heavy metal adsorbent comprising a rare earth compound having high heavy metal adsorbability in a neutral region and low heavy metal adsorbability in an acidic region, wherein the heavy metal adsorbent is unevenly distributed in a thickness direction of the sheet, thereby forming the heavy metal adsorbent-containing layer extending in a horizontal direction of the sheet and a layer which does not substantially contain the heavy metal adsorbent.