To provide a assembly method for a distal end portion of an electronic endoscope in which the connecting strength of the lead wire of a signal wire to the connecting terminal portion of a circuit board can be surely secured and the lead wire of the signal wire can be soldered in a reduced-diameter condition with a uniformity in the outer contour size of a connecting portion within a predetermined size.

In the assembly method, the connecting terminal portion 20 is formed in a groove form, the lead wire 14 of the signal wire 13 is fitted into the connecting terminal portion 20 having the groove form such that its distal end portion extends from the connecting terminal portion 20, the lead wire 14 is secured by soldering 30 to the connecting terminal portion 20, and thereafter the distal end portion of the lead wire 14 extending from the connecting terminal portion 20 is removed.