A new species of the genus Blattisocius Keegan, 1944 is described based on adult females collected from rotting sawdust in Semnan Province, Iran. Blattisocius damghaniae sp. nov. can be distinguished from other species of the genus by some characters, e.g. presence of 33 pairs of relatively short setae on dorsal shield, including z1 and s2; sternal shield longer than wide; ventrianal shield with almost parallel lateral margins, somewhat as wide as epigynal shield, with only three pairs of preanal setae; peritremes short; cheliceral fixed digit slightly shorter than movable digit, with three teeth; movable digit unidentate; genu I with 12 setae.