An imaging device having a color imaging function and an infrared imaging function is provided. The imaging device has a structure in which a first photoelectric conversion device and a second photoelectric conversion device are stacked, and the second photoelectric conversion device generates electric charge by absorbing infrared light and transmits light having a wavelength of a higher energy than that of infrared light. The first photoelectric conversion device is positioned to overlap with the second photoelectric conversion device, and generates electric charge by absorbing light (visible light) passing through the second photoelectric conversion device. Thus, a subpixel for color imaging and a subpixel for infrared imaging can be positioned to overlap with each other, and an infrared imaging function can be added without a decrease in the definition of color imaging.