Abstract: A weighing device includes a housing disposed on an upper end of a post, a displayer disposed on the housing, a piezoelectric element disposed in the housing and having one end located above the opening of the housing, an air bag disposed on a base, a tube coupled to the post and connected to the air bag, and an expandable member disposed on an upper end of the tube for pushing the piezoelectric element when an object is put on the air bag. A signal corresponding to the weight of the object is generated and displayed on the displayer.