A computer input apparatus is used for making a host computer execute a start event according to an instruction of a mobile device. The computer input apparatus includes a mouse pad and an input device. The mouse pad includes a transmission section and an indication section. When the transmission section receives an indication signal from the mobile device, the indication section outputs a sensory signal sensible for humans. The input device has an actuation section. When the input device receives the actuation signal corresponding to the indication signal, the actuation section outputs a start signal to the host computer. Thereby, the host computer executes a start event according to the start signal.