This paper describes the rotation angle sensorless drive of a helical teethed linear actuator (HTLA) for artificial muscle. The position control with vector controller is required the linear and rotary position of the mover of the HTLA. However, to simultaneously measurement the linear and rotary signals is required complicated structure. The proposed estimation method utilizes the magnetic saliency of the mover and linear encoder signal. In this study, the estimation accuracy of the rotation angle was calculated by 3D-FEM analysis and measured by prototype. In addition, we investigated the response characteristics under PID position control using the estimated rotation angle. As the result, the maximum estimation error is 7.5 deg. in the initial stable position of the prototype. Moreover, experimental result show that position control can be performed using the proposed estimation method.