An electrical connection structure includes: a first metal member including copper or a copper alloy, a plated tin layer being formed on at least a portion of the first metal member; a second metal member that is electrically connected or connectable to the first metal member; and a surface treating layer formed on the surface of the first metal member. The surface treating layer is formed by applying a surface treating agent containing base oil and a metal affinity compound having a lipophilic group and an affinity group that has an affinity for metal. The metal affinity compound contains an adduct between an acidic alkyl phosphate ester and an azole compound and an adduct between an acidic alkyl phosphate ester and a metal and/or an organic amine compound.