A loop surface fastener in which numerous looped engaging elements formed from loop yarns inserted in parallel to ground warp yarns are provided upright on one side of a base fabric formed from ground warp yarns and ground weft yarns satisfies all the following requirements 1) to 3). 1) The loop yarn is a multi-filament yarn formed by bundling 5 to 9 filaments of 30 to 45 decitex. 2) The density of the looped engaging elements is in a range of 100 to 200/cm2. 3) Loop surfaces of the looped engaging elements are substantially facing in the same direction and the loop surface facing direction is a ground weft yarn direction.