A method for manufacturing a magnetic field detecting element having a free layer whose magnetization direction is variable depending on an external magnetic field and a pinned layer whose magnetization direction is fixed with respect to the external magnetic field, said free layer and said pinned layer being stacked with an electrically conductive, nonmagnetic spacer layer sandwiched therebetween, wherein sense current is configured to flow in a direction that is perpendicular to film planes of the magnetic field detecting element is provided. The method has the steps of: forming a spacer adjoining layer that is adjacent to said spacer layer, Heusler alloy layer, and a metal layer successively in this order; and forming either at least a part of said pinned layer or said free layer by heating said spacer adjoining layer, said Heusler alloy layer, and said metal layer. The spacer adjoining layer has a layer that is chiefly made of cobalt and iron. The Heusler alloy layer includes metal which is silver, gold, copper, palladium, or platinum, or an alloy thereof. The metal layer is made of silver, gold, copper, palladium, or platinum, or an alloy thereof.