A mounting device, for mounting a plurality of buttons on a product, includes a supporting member, a punching member, and a driving member The supporting member includes a supporting panel, a plurality of holding portions fixed on the supporting panel for supporting the product, a molding board having a plurality of molding holes a platform, and a base fixed on the platform for supporting the molding board. The punching member includes a retaining member positioned above the supporting member, and a plurality of cutters fixed to the retaining member The cutters cut the buttons off a button assembly, and couple to a vacuum generator for creating suction to hold the buttons. The driving member drives the punching member to mount the buttons on the product.