To provide a concrete staircase constructing method which can efficiently construct a concrete staircase by quickly and accurately carrying out troweling work which is finished by conforming a tread front shape of both external portions of a form member to a front shape of an antiskid member.

The form member 1 can mold an antiskid member installing portion 50 on the tread 5 of placed concrete when removed. On both end sides of the form member 1, molded faces 101 are formed which are flush with or substantially flush with a front portion of the tread 5 and an upper portion of a riser surface, respectively, when the staircase is constructed with the use of the form member 1. The form member 1 is set on the upper portion of a riser 4, and concrete is placed. Further, by using a trowel 8 having a smoothing surface formed thereon, which smoothing surface serves as a female form with respect to the molded faces 101, the front portion of the tread 5 and the upper portion of the riser surface are smoothed so as to be flush or substantially flush with the molded faces 101.