There is provided a leaf spring which can prevent a reduction in the spring strength and can also prevent a reduction in the electrical conductivity when the thickness of the leaf spring is decreased. The leaf spring includes an outer frame portion an inner frame portion 5b, 11b disposed inside the outer frame portion 5a, 11a, and spring portions provided between the inner frame portion and the outer frame portion The leaf spring is made of a Cu-based alloy, and has an electrical conductivity of not less than 8% IACS and a 0.2% proof stress of not less than 900 MPa.