A wheel mouse includes a base, a circuit board, a scroll wheel, a wheel swing member, two tilt switches, and a mode-switching element. The wheel swing member has an extension arm. The mode-switching element has an engaging part. The mode-switching element is penetrated through the base and the circuit board and partially protruded outside the surface of the base. By moving the mode-switching element to a first position or a second position, the engaging part is engaged with or separated from the extension arm, so that the wheel mouse is selectively operated in a third-axial wheel operating mode or a tilt wheel operating mode.