Prison House and Central Guard House of the original Abashiri Prison

Five wooden one-storied houses radiate from the Central Guard House. Roofed passages connect these prison houses to the Central Guard House. These houses are called five radiated wings. Clapboards are installed on the exterior walls of the prison houses. Tiles called sangawara were originally used for roofing, but these were replaced with steel sheets.

The prison houses are numbered from north to south. The length in the ridge direction is 58.2m in prison houses No. 1, No. 3 and No. 5, and 72.7m in the prison houses No. 2 and No. 4. In each prison house, cells are placed on both sides of a central corridor. Eighty of the cells in Prison House No. 4 and twenty of the cells in Prison House No. 5 are solitary confinement cells with a space of about 5 m². The remaining cells are shared cells with a space of about 10 m², making a total of 226 cells.

There are skylights with 7mm-thick glass at two places in prison houses No. 1, No. 3 and No. 5, and at three places in prison houses No. 2 and No. 4. To prevent inmates from breaching the walls, the pillars are closely spaced—at intervals of 30cm in shared cells, and at intervals of 21cm in solitary confinement cells.

The roof framework was built by using queen post roof trusses in which the bottom chords were connected by reinforcement bars. At the center, the inverted-Y-shaped end of the reinforcement bars is exposed. The floor of the corridors is paved with bricks, while the cells have wooden floors. Each cell has a toilet in a corner. Interior walls were finished with laths and plaster. The ceiling is flat, made with 15mm-thick smoothly planed boards.

The wall between the corridor and each cell has a wooden door at the center, vertical lattice panels on both sides of the door and a barred window above the door. The cross section of the vertical lattice has a parallelogram or a dogleg shape to keep inmates from looking across the corridor into the opposite cell. The wooden door is a single swing door with a large iron lock, a viewing window in the upper part and a tray slot in the lower part. Inside each cell is a double sliding glass window with a transom 1.5m above the floor. The windows are fitted with iron bars on the outside.

The Central Guard House has an octagonal guard hut at the center that enables the roofed passages leading to the prison houses to be monitored.

From June 24, 2025, seismic retrofitting and conservation repair work is being carried out in the five-wing radial cellblocks, specifically Cellblock No. 1 and Cellblock No. 3, to preserve this Important Cultural Property. During the work period, entry to these cellblocks is not permitted; however, Cellblocks No. 2, No. 4, and No. 5 remain open to visitors as usual.