Ptomaphaginus is a genus of beetles belonging to the family Leiodidae. It contains about 97 species worldwide. Most members live in caves or soil, thus eyes are absent or rudimentary. In 2008, a new species was discovered in the Sunda region. In 2017, two species in Japan were recorded, and 12 new species were discovered in China in 2015.
The following species are recognised in the genus Ptomaphaginus: