The objective of the present invention is to prevent interference of a treadboard with a riser of an adjacent step and generation of a gap between the riser and the treadboard in upper and lower platform parts or in an intermediate inclined part. The escalator is structured so that the riser passes a point whose coordinates in the horizontal and vertical directions are expressed by the expression: krcos[alpha]<SB>m</SB>'-krsin[alpha]<SB>m</SB>(in the expression, k is the speed change ratio; r is the distance between drive roller shafts of steps adjacent to each other in the upper and lower platform parts; and [alpha]<SB>m</SB>is the angle of inclination of the intermediate inclined part) when the end of the treadboard on the upper step side is the origin of the coordinates as the step is viewed from the side with the treadboard being in the horizontal state and on the upper side. |