To provide a Cu-Cr-Zr alloy in which spring properties and solder wettability are simultaneously realized on high levels.

The copper based alloy comprises 0.02 to 0.4% Cr and 0.01 to 0.25% Zr, and the balance Cu with inevitable impurities. In the alloy, 0.2% proof stress is ≥500 MPa, the difference between the 0.2% proof stress and a spring critical value is ≤100 MPa, and the thickness of an oxide film is ≤10 nm.