Retinal prosthesis reconstructs vision by electrically stimulating the remaining normal retinal cells of patients with age-related macular degeneration and retinitis pigmentosa. The purpose of this study is to develop a device that can be safely implanted into patients for a long period. We successfully develop a flexible retinal prosthesis with the CMOS smart electrode array. By mounting CMOS chips in the device, the device can work with only four wirings. Simulating the in-vivo environment using a rat, a biphasic stimulation current waveform is confirmed with our device.