A resistance adjustment circuit has a plurality of conductive patterns placed in parallel to one another on a flat surface formed from an insulating body so as to extend in a first direction, and also has a resistive element that spans two conductive patterns and is electrically connected to the conductive patterns at superimposing parts superimposed on the conductive patterns. A plurality of resistive elements are provided so as to be spaced in the first direction and are connected in parallel to one another across the two conductive patterns. Part of the conductive patterns can be selectively cut between the superimposing parts of resistive elements disposed adjacently. The combined resistance of the resistance adjustment circuit can be adjusted by reducing parallel connections of resistive elements or combining parallel connections of resistive elements with their series connections.
