A strain gauge includes a strain detecting unit and a temperature detecting unit that are formed on or above a flexible substrate. The strain detecting unit includes a resistor formed as a film containing Cr, CrN, and Cr2N, on one surface of a functional layer. A first metallic layer formed of a material of which a gauge factor is less than that of the resistor is laminated on a folded portion, and a resistance value of the first metallic layer on the folded portion is less than a resistance value of the folded portion. The temperature detecting unit is a thermocouple including a second metallic layer formed of a same material as the resistor, on or above the substrate; and a third metallic layer formed of a same material as the first metallic layer, on the second metallic layer.