The tenshu of Hikone-jo Castle was built by transferring and rebuilding Otsu-jo Castle (four layers, five stories) by reducing it to three-layers, and at the renovation (1957-1960) in the Showa period the apparently diverted components in the materials of the tenshu were found.
大津城天守（4重5階）を3重に縮小して移築したといわれ、昭和の天守解体修理（-）のときに、天守の用材から転用されたものと見られる部材が確認されている。