A button switch includes a base having a pillar, a cover disposed on the base, a sleeve, an arm adjacent to the pillar and an elastic member having upward-force-applying, extending-rod, and flexible-rod portions. The sleeve jackets the pillar, passes through the cover, and has first and second ribs. The upward-force-applying portion jackets the pillar and abuts against the sleeve and the base to drive the sleeve to move away from the base. The extending-rod portion extends from the upward-force-applying portion to be connected to the flexible-rod portion located under the first rib. When the sleeve is located at a high position, the second rib biases the arm to deform. When the sleeve is located at a low position, the second rib is misaligned with the arm. The flexible-rod portion crosses the first rib to be released and then collides with the cover to make sound as the sleeve is pressed.