A method for manufacturing a magnetic field detecting element has the steps of: forming stacked layers by sequentially depositing a pinned layer, a spacer layer, a spacer adjoining layer which is adjacent to the spacer layer, a metal layer, and a Heusler alloy layer in this order, such that the layers adjoin each other; and heat treating the stacked layers in order to form the free layer out of the spacer adjoining layer, the metal layer, and the Heusler alloy layer. The spacer adjoining layer is mainly formed of cobalt and iron, and has a body centered cubic structure, and the metal layer is formed of an element selected from the group consisting of silver, gold, copper, palladium, or platinum, or is formed of an alloy thereof.