To provide stairs having a beautiful external appearance and excellent construction properties.

Footboards 1 are laid over between opposite horizontal step parts 3a in a pair of strings 3 and fixed and a riser 2 is provided between the fore end part of an upper footboard 1A and the rear end part of a lower footboard 1B and fitted to each of them. Each footboard 1 is set on and fixed to the horizontal step parts 3a. As for each riser 2, the upper end 2a thereof is brought into contact with the lower side of the fore end part of the upper footboard 1A, the back 2b thereof with a vertical part 3b and the front 2c of the lower end part thereof with the rear end face of the lower footboard 1B, and they are fixed. A guide part 4 for guiding fitting of the riser 2 is provided at the lower end part of the vertical part 3b and a space S is formed between the guide part 4 and the back of the riser 2.