To provide a partition wall easily assemblable or disassemblable and re-usable after disassembling.

In this partition plate 1, a pair of plate members 2 formed of a synthetic resin foam material are oppositely joined to each other through hollow layers 3. The hollow layers 3 are formed of projecting parts 4 formed on a spacer 9 between the plate members 2 or the opposed surfaces of the plate members. As necessary, reinforcing insertion members 6 are removably inserted into insertion slits 5 formed in the inner and outer surfaces and both side surfaces of the plate members 2.