A treadmill comprising: a frame structure; a track part capable of rotating with respect to the frame structure; and a rotation unit disposed in the frame structure and rotatably supporting the track part, wherein the track part comprises: a plurality of slats arranged in a rotation direction; and a track belt disposed at both end portions of the plurality of slats and connecting the plurality of slats, the rotation unit comprises: first rotation members disposed in front and rear of the frame structure; and a plurality of second rotation members disposed between the first rotation members, having a diameter less than a diameter of each of the first rotation members, and arranged according to an upper shape of the frame structure, and at least one of the first rotation members includes a plurality of grooves arranged apart from each other on an outer circumferential surface of the at least one of the first rotation members in a circumferential direction; the at least one of the first rotation members has a surface shape different from an inner circumferential surface of the track belt, characterized in that the outer circumferential surface of the at least one of the first rotation members comprises a plurality of non-contact areas in which the plurality of grooves are formed and a plurality of contact areas disposed between the plurality of grooves and contacting the track belt. a frame structure; a track part capable of rotating with respect to the frame structure; and a rotation unit disposed in the frame structure and rotatably supporting the track part, wherein the track part comprises: a plurality of slats arranged in a rotation direction; and a track belt disposed at both end portions of the plurality of slats and connecting the plurality of slats, the rotation unit comprises: first rotation members disposed in front and rear of the frame structure; and a plurality of second rotation members disposed between the first rotation members, having a diameter less than a diameter of each of the first rotation members, and arranged according to an upper shape of the frame structure, and at least one of the first rotation members includes a plurality of grooves arranged apart from each other on an outer circumferential surface of the at least one of the first rotation members in a circumferential direction; the at least one of the first rotation members has a surface shape different from an inner circumferential surface of the track belt, characterized in that the outer circumferential surface of the at least one of the first rotation members comprises a plurality of non-contact areas in which the plurality of grooves are formed and a plurality of contact areas disposed between the plurality of grooves and contacting the track belt. a plurality of slats arranged in a rotation direction; and a track belt disposed at both end portions of the plurality of slats and connecting the plurality of slats, the rotation unit comprises: first rotation members disposed in front and rear of the frame structure; and a plurality of second rotation members disposed between the first rotation members, having a diameter less than a diameter of each of the first rotation members, and arranged according to an upper shape of the frame structure, and at least one of the first rotation members includes a plurality of grooves arranged apart from each other on an outer circumferential surface of the at least one of the first rotation members in a circumferential direction; the at least one of the first rotation members has a surface shape different from an inner circumferential surface of the track belt, characterized in that the outer circumferential surface of the at least one of the first rotation members comprises a plurality of non-contact areas in which the plurality of grooves are formed and a plurality of contact areas disposed between the plurality of grooves and contacting the track belt. first rotation members disposed in front and rear of the frame structure; and a plurality of second rotation members disposed between the first rotation members, having a diameter less than a diameter of each of the first rotation members, and arranged according to an upper shape of the frame structure, and at least one of the first rotation members includes a plurality of grooves arranged apart from each other on an outer circumferential surface of the at least one of the first rotation members in a circumferential direction; the at least one of the first rotation members has a surface shape different from an inner circumferential surface of the track belt, characterized in that the outer circumferential surface of the at least one of the first rotation members comprises a plurality of non-contact areas in which the plurality of grooves are formed and a plurality of contact areas disposed between the plurality of grooves and contacting the track belt.