A circulating module of a linear guideway includes a slider and a circulator. The slider has two carrying surfaces arranged on two opposite outer surface thereof. Each carrying surface includes a first circular-arc segment and two second circular segments respectively arranged at two opposite sides of the first circular-arc segment, and a radius of each first circular-arc segment is smaller than that of each second circular-arc segment. The circulator includes two inner circular-arc surfaces. The slider is inserted into the circulator, the carrying surfaces stretch a distance between the inner circular-arc surfaces, each inner circular-arc surface is abutted against the two second circular-arc segments of the corresponding carrying surface, and a gap is formed between each inner circular-arc surface and the corresponding first circular-arc segments.