An assembly method for an electronic apparatus is assembling an electronic apparatus by performing coupling work of a branched flat cable including a base end portion and a first end portion and a second end portion branched from the base end portion and having flexibility using an assembly apparatus. The assembly apparatus includes a suction unit, a gripping unit, a robot arm unit, and a control unit. The method includes a first gripping step of gripping a first end portion, a first coupling step of coupling the first end portion to a first connector, a first release step of releasing the gripping, a suction step of suctioning a second end portion, a second gripping step of gripping the second end portion, a second coupling step of coupling the second end portion to a second connector, and a second release step of releasing the gripping of the second end portion.