A device having a liftable strap supply reel includes a housing, a liftable mechanism and a pushing force generator. The liftable mechanism is pivoted on the housing and it has a first arm that is disposed with a rotatable strap supply reel. The liftable mechanism contains a home position, a critical position, and a lift-up position. When this lifting mechanism is positioned at the lift-up position, the pushing member generates a force to create a torque so that the strap supply reel stays at a height near a waist of a human. So, the strap supply reel can be lifted up to a height approximately near a waist of a human. It can be operated by one hand. In addition, it is convenient to repair or replace the strap.