A box-shaped ready-to-assemble toilet is made of corrugated board or cardboard. The ready-to-assemble toilet includes first to fourth sidewall portions and a bottom portion. Each of the first to fourth sidewall portions includes an outer sidewall, an inner sidewall and a horizontal wall. The horizontal walls of the first and second sidewall portions overlap each other. The horizontal walls of the second and third sidewall portions overlap each other. The horizontal walls of the third and fourth sidewall portions overlap each other. The horizontal walls of the fourth and first sidewall portions overlap each other.