To provide an assembly bath which saves a space since it requires a small occupying space by housing it in a compact manner when it is not used and is used by assembling it easily and quickly when it is needed.

A bathtub part 11 is formed by using a plastic corrugated board as a material to make a box body of a prismoidal shape by joining by a removable tape. A reinforcing material 12 using the plastic corrugated board as the material is superposed on the bathtub part 11. Frame parts 13a, 13, 14a, 14b using the plastic corrugated board as the material are provided at upper end parts of the bathtub part 11. Pipes 21a, 21b and bar materials 31a, 31b are mounted on the frame parts 13a, 13, 14a, 14b. An opening and closing valve 15 to which a water discharging hose 16 is connected is attached to the bathtub part 11. A hot water collecting bag for collecting the hot water to be supplied is housed inside the bathtub part 11.