A rail configured to guide a carriage is provided. The rail includes a first unit and a second unit; and a coupling mechanism. The coupling mechanism is configured to couple a first target member, which is a coupling target that is either a first support or a first rack, to a second target member, which is a coupling target that is a second support or a second rack. The coupling mechanism includes a coupling member; a first fixing member; and a second fixing member. The first fixing member is configured to position the first target member and the coupling member, and the second fixing member is configured to adjust relative positions of the second target member and the coupling member, and is configured to fix the second target member and the coupling member at adjusted relative positions.