To provide a device for adjusting an electronic device, in which rattling between an input shaft and a driving gear due to backlash of the gear is eliminated by providing the driving gear with a fitting part which fits into the input shaft of a variable resistor.

A driving shaft 65 has a spline-shaped groove 65a which is engaged with the lower end part of a driving gear 61 and a fitting part 65b which fits into an input shaft 43 of a variable resistor 4. When the driving gear 61 rotates, the driving shaft 65 and the input shaft 43 accordingly rotate. In this case, there is no rattling between the driving gear 61 and the input shaft 43 due to backlash in the gear. The rotational force of the driving gear 61 is directly transmitted from the driving shaft 65 to the input shaft 43, so that the load on the variable resistor 4 does not act on a gear train 60 and the size of the teeth of the gear can be reduced. Thus, a fine adjustment can be performed and the device can be made thinner and smaller.