To provide a sliding door structure of an assembly house having a simple structure and therefore facilitating manufacture of members and the assembly work.

A downward guide groove 10 and a downward inner guide wall 11 are arranged on a lower frame 7. An outer sliding door 3 is restricted from swinging by a swing preventing frame 12 extending from the lower part of the outer sliding door 3 to the guide groove 10 passing under an inner sliding door 4, and by an outer sliding door guide piece 20 mounted on the swing preventing frame 12. A closing end side of the inner sliding door 4 is restricted from swinging by an outer guide wall 14 formed on the swing preventing frame 12 in a manner of facing the inner guide wall 11, a closing end swing preventing plate 16 mounted on a lower part of the sliding door 4 and positioned between the inner guide wall 11 and the outer guide wall 14, and a guide runner 20 mounted on a lower part of the closing end side of the closing end swing preventing plate 16. An opening end side of the sliding door 4 is restricted from swinging by a swing preventing arm plate 18 extending from a lower part of the opening end side to the guide groove 10, and an inner sliding door guide piece 22 mounted on the swing preventing arm plate 18.