To provide a printing drum and a stencil printing device that cause no wrong detection of a master even in the occurrence of oil penetration in the master.

In a printing drum equipped with a plate cylinder, a screen, a porous elastic body, and a master, between an ink non-passable member and the master, another non-passable member is inserted which has an open part formed for the purpose of preventing adherence of the ink non-passable member with the master and detecting presence/absence of the master by an optical sensor.