A mobile device and a corresponding proximity detection method are provided. The mobile device includes an infrared emitter and a proximity sensor. The infrared emitter emits an infrared using first power in a first mode or emits the infrared using second power in a second mode. The first power and the second power are different. The proximity sensor detects the reflection of the infrared and determines whether or not there is an object in close proximity to the mobile device based on the reflection.