A display unit having a function of sensing light is provided. The display unit includes a first and second light-emitting devices, a light-receiving device, and a light-blocking layer. The first and second light-emitting devices emit a first color. The light enters the light-receiving device through a first opening of the light-blocking layer. In a top view, |a−b| of a difference between the shortest distance a from the first light-emitting device to the light-receiving device and the shortest distance b from the second light-emitting device to the light-receiving device is smaller than |c−d| of a difference between the shortest distance c from the first light-emitting device to the first opening and the shortest distance d from the second light-emitting device to the first opening. In the top view, c is shorter than d. Alternatively, a light-emitting and light-receiving device can be used.