A multiple position adjustable exercise device, comprising: a first member; a second member, wherein the first member is pivotally connected with the second member; and an elastic member disposed in the second member, wherein when the first member rotates relative to the second member, the elastic member is stretched or compressed for providing an elastic recovering force; the multiple position adjustable exercise device characterized by further comprising: a switch (219, 315) coupled with the first member and the second member; a belt, wherein one end of the belt is connected with the elastic member; a belt reel disposed between the first member and the second member, wherein the switch (219, 315) is linked with the belt reel; at least one guiding wheel, wherein the other end of the belt is linked with the belt reel through the guiding wheel; a compression spring (217, 317), wherein the belt reel is linked with the compression spring (217, 317); and a tooth sleeve disposed between the first member and the second member, wherein the belt reel is detachably connected with the tooth sleeve; wherein when the first member rotates relative to the second member, the belt reel is rotated, and the belt is guided by the guiding wheel to stretch or compress the elastic member; wherein when the belt reel is linked by the switch to compress the compression spring (217, 317), the belt reel is detached from the tooth sleeve, and an initial position of the first member relative to the second member is adjustable; wherein when the belt reel is linked by the switch to release the compression spring (217, 317), the belt reel is pushed to be combined with the tooth sleeve through the elastic recovering force of the compression spring (217, 317), and the initial position of the first member relative to the second member is fixed. a first member; a second member, wherein the first member is pivotally connected with the second member; and an elastic member disposed in the second member, wherein when the first member rotates relative to the second member, the elastic member is stretched or compressed for providing an elastic recovering force; the multiple position adjustable exercise device characterized by further comprising: a switch (219, 315) coupled with the first member and the second member; a belt, wherein one end of the belt is connected with the elastic member; a belt reel disposed between the first member and the second member, wherein the switch (219, 315) is linked with the belt reel; at least one guiding wheel, wherein the other end of the belt is linked with the belt reel through the guiding wheel; a compression spring (217, 317), wherein the belt reel is linked with the compression spring (217, 317); and a tooth sleeve disposed between the first member and the second member, wherein the belt reel is detachably connected with the tooth sleeve; wherein when the first member rotates relative to the second member, the belt reel is rotated, and the belt is guided by the guiding wheel to stretch or compress the elastic member; wherein when the belt reel is linked by the switch to compress the compression spring (217, 317), the belt reel is detached from the tooth sleeve, and an initial position of the first member relative to the second member is adjustable; wherein when the belt reel is linked by the switch to release the compression spring (217, 317), the belt reel is pushed to be combined with the tooth sleeve through the elastic recovering force of the compression spring (217, 317), and the initial position of the first member relative to the second member is fixed. a switch (219, 315) coupled with the first member and the second member; a belt, wherein one end of the belt is connected with the elastic member; a belt reel disposed between the first member and the second member, wherein the switch (219, 315) is linked with the belt reel; at least one guiding wheel, wherein the other end of the belt is linked with the belt reel through the guiding wheel; a compression spring (217, 317), wherein the belt reel is linked with the compression spring (217, 317); and a tooth sleeve disposed between the first member and the second member, wherein the belt reel is detachably connected with the tooth sleeve; wherein when the first member rotates relative to the second member, the belt reel is rotated, and the belt is guided by the guiding wheel to stretch or compress the elastic member; wherein when the belt reel is linked by the switch to compress the compression spring (217, 317), the belt reel is detached from the tooth sleeve, and an initial position of the first member relative to the second member is adjustable; wherein when the belt reel is linked by the switch to release the compression spring (217, 317), the belt reel is pushed to be combined with the tooth sleeve through the elastic recovering force of the compression spring (217, 317), and the initial position of the first member relative to the second member is fixed.