This paper presents a self-tuning speed control scheme for the surface-mounted permanent magnet synchronous motor (SPMSM) against parameter variations with the traditional vector control strategy. The proposed control strategy has three novelties; the first one is to design the inner- and outer-loop controllers to stabilize the current and speed dynamics with the self-tuning algorithm for a better transient performance, the second one is to give a systematic way to constitute a robust optimal control gain by solving an optimization problem, and the third one is to show that the proposed inner-loop controller also stabilizes the closed-loop system, including the first-order internal dynamics caused by the SPMSM speed. The efficacy of the proposed method was verified through experiments using a 3-kW SPMSM.