A physical quantity sensor includes a substrate, a pair of first elements detecting acceleration in a first direction, and a pair of second elements detecting an acceleration in a second direction. The first element portion includes a first movable portion displaceable in the first direction, first and second movable electrode fingers disposed in the first movable portion, first and second fixing electrode fingers disposed to face the first and second movable electrode fingers, and first and second support portions supporting the first and second fixing electrode fingers. The second element includes a second movable portion displaceable in the second direction, third and fourth movable electrode fingers disposed in the second movable portion, third and fourth fixing electrode fingers disposed to face the third and fourth movable electrode fingers, and third and fourth support portions supporting the third and fourth fixing electrode fingers.