The invention discloses an image sensor. Compared with an existing image sensor, due to the fact that an existing visible light sensing unit in a Bayer format is reserved in a center area of a light sensing unit array and an infrared light sensing unit is added in the marginal area, the intensity of infrared light and the intensity of the visible light can be obtained through only one two-way light filter, and the cost of the light filter and a switching mechanism is reduced. In the daytime, the intensity of the visible light and the intensity of the infrared light can be worked out by means of the light sensing unit in the center area and the light sensing unit in the marginal area, so that the color accuracy of a daytime image is ensured; at night, the light sensing unit in the center area can receive the energy of the visible light and the energy of the infrared light at the same time, and the night image brightness is increased. In addition, due to the fact that the infrared light sensing unit is arranged on the marginal area of the light sensing unit array, compared with the existing image sensor, the positions of redundant light sensing units on the periphery of the image sensor are just utilized, and the area of the image sensor will not be increased.