The present strain gauge includes a substrate having flexibility; a resistor formed from a material containing at least one of chromium and nickel, on the substrate; a pair of wiring patterns formed on the substrate and electrically connected to both ends of the resistor; and a pair of electrodes formed on the substrate and electrically connected to the pair of wiring patterns, respectively. The wiring patterns include a first layer extending from the resistor, and a second layer having a lower resistance than the first layer and layered on the first layer. On the substrate, an electronic component mounting area is demarcated, on which an electronic component electrically connected to the electrodes is mounted.