Provided is a magnetic field detection device that includes a first soft magnetic body and a magnetic detector. The first soft magnetic body includes a first plate and a first protrusion. The first plate includes a first surface including a first outer edge. The first protrusion is provided at a first arrangement position in the first surface and includes a first tip on opposite side to the first surface. The first arrangement position is set back from the first outer edge. The magnetic detector is provided in the vicinity of the first tip.