According to one embodiment, a solid-state imaging device includes an output level determining unit, a random number data generating unit, and an output selecting unit. The output level determining unit performs a level determination of a digital output signal by comparing a level of the digital output signal with a threshold value. The random number data generating unit generates random number data by random number processing on the level of the digital output signal. The output selecting unit selects any of: the digital output signal subjected to an addition of the random number data, and the digital output signal not subjected to the addition of the random number data corresponding to a result of the level determination.