To provide a physical quantity detector capable of preventing a joint failure of a wire and breakage of a sensor in ultrasonic bonding, and excelling in impact resistance.

The physical quantity detector 20 includes a sensor part 19 mounted on a board 7. In the sensor part 19, a weight part 1 is jointed to a frame part 3 through a pair of beam parts 2, and suspended in an opening of the frame part 3. A lower lid 4 is jointed to a lower part of the frame part 3. Pad electrodes 5 are arranged on the upper parts of the frame part 3, and electrically connected to board electrodes 8 arranged on the board 7 through connection wires 6. The sensor part 19 is supported on the board 7 from the lower side of the lower lid 4 by support members 9. The support members 9 support the sensor part 19 on the board 7 in a state fixed to either of the sensor part 19 or the board 7. The sensor part 19 supported to the support members 9 is fixed to the board 7 by an elastic adhesive 10. The support member 9 is formed with a member having hardness higher than that of the elastic adhesive 10.