PURPOSE: To easily manufacture various formed items in continuous lengths by a method wherein the ends of forming stock having poor thermal fusion-weldability are formed into a specified fitting structure so as to be successively and closely engaged with each other.

CONSTITUTION: When the pressing of a first forming stock X is finished, the whole top force 10 is raised and the formed body X is shifted forward forwards. The positioning of the formed body X is done by fitting the part to be engaged 20 at the rear end of the formed body X to a positioning groove 19. Next, a next forming stock x1, which is softened by heating, is fed between a press tool 8 and a bottom force 11 in such a manner that the front end part of the forming stock x1 overlaps to the part to be engaged 20 of the formed body X. After that, the whole top force 10 is lowered so as to pressingly fix the previous formed body X with a hold-down force 9 and, after that, press the forming stock x1 with the press tool 8 in order to turn the stock x1 into a formed body x1. Since the front end part of the forming stock x1 is pinched between the recessed groove 18 for forming an engaging part and the part to be engaged 20 at the rear end of the previous formed body X so as to strongly integrate both the bodies X and X1 with each other in order to form a formed item in continuous lengths.