Abstract: A hands-free device for a mobile phone including an upper casing having a built-in speaker and a lower casing having a magnet to hold the mobile phone is disclosed. The hands-free device includes means for connecting said upper and lower casing to allow the upper casing to rotatably close and open relative to said lower casing, and also includes means for limiting a maximum opening angle of the upper casing. Microphones having a directional input angle of 180 degree or less, which are connected to a same phase signal canceling circuit, are provided to eliminate the incoming background noise.