A magnetic field detection device includes a base, a first yoke, and a magneto-resistive effect element. The first yoke is provided on the base, and includes first and second principal surfaces each extending along a first plane, and a first end surface coupling the first and second principal surfaces. The magneto-resistive effect element is provided on the base, and includes a magnetization free layer disposed at a position overlapped with the first yoke in a first direction along the first plane. The first end surface includes an inverted tapered surface inclined relative to the first plane and extending closer to a center point of the magnetization free layer as being away from the base in a second direction orthogonal to the first plane. A distance from the center point to a first edge is shorter than a distance from the center point to a second edge.