PURPOSE: To mold a connecting protrusion of a switch button at high dimensional accuracy of the same, by a method wherein a pair of groove parts is provided on both sides of a linear protrusion of a core pin and protective protrusions are formed respectively on both side surfaces of a slit of the switch button, which are confronting with each other, through the groove parts.

CONSTITUTION: Protective protrusions 1g, 1g are provided respectively on both side surfaces of slit (e), which are confronting with each other, and a pair of groove parts 2e, 2e is provided on both sides of a linear protrusion 2c. Under a state wherein a core pin 2 and a plurality of molds corresponding to external shape of a switch button 1 are combined, a molten resin material is injected and cast into a cave part to be formed among these molds and the molds other than the core pin 2 are removed after cooling. At the time of removal of the switch button 1 from the core pin 2, as a connecting protrusion 1f does not abut against a head part 2b of the core pin 2 due to a matter that the protective protrusion 1g is pulled out while the slit (e) is being pushed up under a state wherein only the protective protrusion 1g is abutted against the linear protrusion 2c, flaws are not generated on the connecting protrusion 1f.