A holder and a sucker thereof for mounting onto the surface of an object are provided. The sucker has an adhesive layer and a deformable body which is disposed on the edge of the adhesive layer. The holder further includes a rod and a locking module. An end of the rod is connected to the sucker. The locking module is disposed on the sucker and is adapted to lift the rod to form a low pressure space. Thus, the holder and the sucker can be positioned onto the surface of the object.