A holder for sustaining a handheld electronic device is provided. The holder includes a sucker and a positioning device. The sucker has a central and peripheral portion. The positioning device, which is disposed on a side of the sucker, comprises a housing, a ball, a clamping assembly and a rod. The housing is disposed on the sucker and has a receiving space for the ball and the clamping assembly. The rod has a first end connecting to the central portion of the sucker and a second end extending towards the receiving space. When the rod is led to position the sucker onto an object, the clamping assembly is adapted to restrict the ball simultaneously.