STAIRCASE STRUCTURE, FIXTURE AND ASSEMBLY METHOD OF STAIRCASE STRUCTURE

PROBLEM TO BE SOLVED: To provide a staircase structure in which productivity and workability are high and appearance and a strength to a load can be improved, respectively, and fixture and an assembly method of the staircase structure.SOLUTION: In a distal end portion and an outer surface of a vertical surface part 41 of an angle-shaped fixture 4L, first and second protrusions 43, 44 are integrally provided which are longer than thickness of the angle and protrude outside. A worker fixes the vertical surface part 41 of the fixture 4L to a stringer board 13 by machine screws in the state where the first and second protrusions 43, 44 are fitted to first and second fitting grooves 53, 54 formed on the stringer board, and then fixes a horizontal surface part 42 to a bottom face of a step board with machine screws.