A continuously adjustable rotation device includes a base, a first connection element combined with the base, a ring buckle, a transmission disc, a second connection element, and a rotation controller. The transmission disc is formed on the contacting portion of the base, forming an inclination angle and contacting the second connection element for transmission of force. By using the rotation controller, one can select a rotation direction by properly contacting with the transmission disc. When the rotation direction is selected, the second connection element and the transmission disc then drive the first connection element to rotate in the designated direction. One can thus perform a continuously adjustable rotation. Therefore, no alignment is needed when assembling the rotation device, which will enhance the production yield and lower the manufacturing cost.