A disassembling accessory for disassembling a physiological signal monitoring device includes a base seat having an accommodating space, and a cover body connected to the base seat and movable between covering and open states. The physiological signal monitoring device includes a sensor kit having an through hole, and a transmitter removably mounted to and covering the sensor kit. The cover body has a button being movable and a pushing member connected co-movably to the button. When the cover body is in the covering state, the button is operable to drive the pushing member to move such that the pushing member extends through the through hole to push the transmitter for disassembling the transmitter from the sensor kit.