A computer mouse includes a lower shell, an upper shell mounted to the lower shell, a resilient member, and a converting unit. The upper shell includes two rotating portions rotatably mounted to the lower shell. A resisting post extends from each rotating portion, and resists against the resilient member. The rotating portion can be slidably clamped via the converting unit, and then the rotating portions are prevented from rotating away from each other. The rotating portions can be rotated towards each other, and the elasticity of the resilient member drives the rotating portions away from each other.