Abstract: A one-way self-locking device for a massager includes a transmission shaft, a shaft sleeve, a torsional spring, and a big belt wheel. The big belt wheel is rotatably sleeved on the transmission shaft, and the big belt wheel is driven by a power mechanism to drive the transmission shaft to circumferentially rotate. The shaft sleeve is fixedly mounted on the transmission shaft. The torsional spring is sleeved on the shaft sleeve. A first connecting portion of the torsional spring is in interference fit with the shaft sleeve, a main body portion of the torsional spring is sleeved on the shaft sleeve and is in clearance fit with the shaft sleeve, and a second connecting portion of the torsional spring is fixedly connected to the big belt wheel to achieve one-way self-locking.