A feeding device includes a storage mechanism and an adsorbing mechanism. The storage mechanism includes two side plates substantially parallel to each other, two support members slidably coupled between the two side plates, two driving members, and two feeding trays. The driving members are mounted to one of the two side plates and coupled to the corresponding support members. The driving members are configured to drive the two support members to move out of the storage mechanism one at a time. The feeding trays are configured for receiving workpieces and coupled to the corresponding support members.