Disclosed is a method of forming a chained product of metal-base circuit boards, wherein position dimensions between each of the circuit patterns can be maintained, even when press processing a bend-splitting structure. The method of forming a chained product of metal-base circuit boards is provided with: a chained product forming process for forming circuit patterns (7) with preset gaps interposed therebetween, on a metal substrate with an insulation layer (5) interposed therebetween, and forming a chained product (1) of circuit boards (9) each of which is provided with the circuit pattern (7); a notch forming process for partially forming, by press processing, notches (11, 13) for bend-splitting separation of the circuit boards (9), on lines where the bend-splitting separation is scheduled to be executed; and a slit forming process for forming slits (15, 17, 19) in penetration on the lines, leaving the notches (11, 13) intact.