In this work, the erosion-corrosion resistance of wrought copper, brass (JIS C3771), and bronze casting (JIS CAC411) was evaluated by the jet-in-slit test using an electrochemical technique. The specimen holder was newly modified to be equipped with a reference electrode. Analysis by Computer-Aided Engineering confirmed that influence of the flow of the test solution was minimized by attaching the reference electrode, and that shear stress and turbulent flow kinetic energy at the specimen surface were larger in the center area than in the outer area. The specimens were measured for the corrosion potential, polarization curve, and galvanic current between the disk in the center and ring on the outside of the specimen. Cathodic and anodic current densities increased when the test started. Cathodic current density was independent of the type of copper alloy and decreased slightly with increasing test time. On the other hand, anodic current density was different among the copper alloys. For copper and C3771 which suffered erosion-corrosion, corrosion product layers hardly grew, and anodic current densities did not decrease during the test. Immediately after the test, their corrosion potentials greatly changed. The positive galvanic (i.e. anodic) current was detected from the specimen’s disk part, which as estimated to suffer more mechanical impact from the solution flow. In the case of CAC411, which did not exhibit erosion corrosion, corrosion product layer grew, and anodic current density decreased with increasing test time. The corrosion potential did not much change immediately after the test finished. The galvanic current of CAC411 was smaller and the current direction was opposite to those of copper and C3771. It was concluded that the erosion-corrosion resistance of bronze casting CAC411 was better due to the formation of the corrosion product layer, which grew even under high shear stress and turbulent flow kinetic energy, and suppressed the anodic reaction of the substance.