A strain gauge includes a flexible substrate, and a resistor formed of material containing at least one from among chromium and nickel, on or above the substrate. The resistor includes a first layer that is a lowermost layer; and a second layer that is a surface layer laminated on or above the first layer. The second layer is a layer having a higher density than the first layer. The first layer has a first surface provided on a side where the flexible resin substrate is situated, the functional layer being laminated on the first surface. The first layer has a second surface on which the second layer is laminated.