Spinal subdural hematoma(SSDH) is rare disease. Furthermore, it rarely occurs as a complication of intracranial surgery. There are few case reports which describing SSDH after craniotomy. Although the exact pathogenetic mechanism is obscure, some investigators propose that downward migration of intracranial hematoma by the effect of gravity is one of the cause of SSDH, and which is commonly suggested. But others propose that cerebrospinal fluid(CSF) hypotension is an another possible mechanism. In this paper, we report two cases of SSDH after clipping of an aneurysmal neck.