A mechanical-quantity measuring device capable of measuring a strain component in a specific direction with high precision is provided.At least two or more pairs of bridge circuits are formed inside a semiconductor monocrystal substrate and a semiconductor chip, and one of these bridge circuits forms a n-type diffusion resistor in which a direction of a current flow and measuring variation of a resistor value are in parallel with a direction of the semiconductor monocryastal silicon substrate, and an another bridge circuit is composed of combination of p-type diffusion resistors in parallel with a direction.