A watch type mobile terminal includes: a body having a power supply unit, a printed circuit board, and a display unit formed to implement a touch input thereon; a band unit formed to be wearable on a user's wrist by being connected to the body, and formed such that at least part thereof is wound or unwound in the body; and a length control unit configured to implement winding or unwinding of the band unit such that a length of the band unit is controllable in accordance with a user's wrist size.