A case structure for accommodating a circuit board of an implantable electronic device includes a housing and a lid body. The housing has a plate portion, a wall portion and an opening. One end of the wall portion connects to the periphery of the plate portion, and the other end of the wall portion defines the opening. The periphery of the plate body is sealed with the other end of the wall portion. Accordingly, the plate body and the housing together form an airtight space for accommodating the circuit board.
