A starter solenoid switch according to the present invention includes a first and a second set of contacts that are disposed between a battery and a starter motor in parallel with each other. The first and the second sets of contacts are so configured that the second set of contacts is closed to supply a lighter electric current to the starter motor before the first set of contacts is closed to supply a heavier electric current to the same. The second set of contacts is composed of a second fixed contact and a second movable contact, one of which includes a low-resistance portion at one end thereof and a high-resistance portion that contains more carbon than the low-resistance portion. The low-resistance and the high-resistance portions are serially disposed along a conducting path of electric current from the battery to the starter motor, thereby ensuring reliability of the starter solenoid switch.