A magnetic field detection device includes a first soft magnetic body, a second soft magnetic body, and a magnetism detection element. The first soft magnetic body extends to have a first length in a first direction, and has a first width, smaller than the first length, in a second direction. The second direction is substantially orthogonal to the first direction. The second soft magnetic body is disposed to be spaced apart from and face the first soft magnetic body in the first direction, extends to have a second length in the first direction, and has a second width, smaller than the second length, in the second direction. The magnetism detection element is disposed, in the first direction, between the first and second soft magnetic bodies, and extends to have a third length in the first direction and a third width, larger than the third length, in the second direction.