We have successfully observed Faradaic current in cyclic voltammetry of an amorphous Ge2Sb3.4Te6.2 film with Ag electrodes. The Faradaic current peak was attributed to a non-reversible redox process limited by diffusion of Ag cations. The Ag cations can be generated by anodic dissolution under applied bias voltage or may exist before the voltage application as "ready-made" ions. The cyclic voltammetry demonstrated the existence of ready-made Ag cations. The concentration of the ready-made cations was 0.008 mol/cm(3), which was about one-tenth of the cations formed by a voltage sweep at 3.6 V/s, and was about one-hundredth of those formed at 0.3 V/s.