A central axis variable device for varying the central axis of a wheel, the central axis variable device comprising: a rotating body along the inner circumference of which a first uneven portion is formed and both sides of which are pierced with respect to each other; a first cap that is combined at one side of the rotating body; a second cap along the outer circumference of which a second uneven portion is formed in correspondence to the first uneven portion to thus be combined at the other side of the rotating body, and on which a shaft tube is formed; characterized in that an eccentricity hole is formed on an eccentric portion of the first cap; that the shaft tube is inserted into the eccentricity hole; that a coupling hole is formed at the first cap, an engagement hole corresponding to the coupling hole is formed at the second cap, and that a coupling member passes through the coupling hole and the engagement hole and couples the first and second caps (200, 300) with each other, that a bent piece is formed inwards from the rotating body along the border of one side of the rotating body; that a separation preventive member is detachably formed in the inner surface of the first cap, and that interferes with the bent piece, to thus prevent the rotating body and the first cap from being separated from each other; that a step groove is stepped toward the engagement hole and is formed at the side of the second cap; and that an interference protrusion has an elastic force to come in and out toward the step groove and is formed in the inner side of the second cap, wherein the coupling member comprises a head portion on which a plurality of grooves are formed so that the interference protrusion is arranged into one of the plurality of grooves, and that a thread portion is extended from the head portion, and is exposed through the coupling hole of the first cap, to then be engaged by a nut. a rotating body along the inner circumference of which a first uneven portion is formed and both sides of which are pierced with respect to each other; a first cap that is combined at one side of the rotating body; a second cap along the outer circumference of which a second uneven portion is formed in correspondence to the first uneven portion to thus be combined at the other side of the rotating body, and on which a shaft tube is formed; characterized in that an eccentricity hole is formed on an eccentric portion of the first cap; that the shaft tube is inserted into the eccentricity hole; that a coupling hole is formed at the first cap, an engagement hole corresponding to the coupling hole is formed at the second cap, and that a coupling member passes through the coupling hole and the engagement hole and couples the first and second caps (200, 300) with each other, that a bent piece is formed inwards from the rotating body along the border of one side of the rotating body; that a separation preventive member is detachably formed in the inner surface of the first cap, and that interferes with the bent piece, to thus prevent the rotating body and the first cap from being separated from each other; that a step groove is stepped toward the engagement hole and is formed at the side of the second cap; and that an interference protrusion has an elastic force to come in and out toward the step groove and is formed in the inner side of the second cap, wherein the coupling member comprises a head portion on which a plurality of grooves are formed so that the interference protrusion is arranged into one of the plurality of grooves, and that a thread portion is extended from the head portion, and is exposed through the coupling hole of the first cap, to then be engaged by a nut.