A method of manufacturing a semiconductor device, forms connection pads electrically connected to integrated circuit portion formed in a semiconductor substrate, lays an insulating film and a protective film one over another, forms sub-lines electrically connected to the connection pads on the protective film, forms a coating film covering the sub-lines and the protective film, sticks a dry film onto the coating film, forms external connection electrodes externally connectable and electrically connected to the sub-lines, and removes the dry film and forms a sealing layer covering the coating film and side surfaces of the external connection electrodes.