An imaging device includes an exposure control unit, a determination unit, and an illuminance calculation unit. The exposure control unit is configured to control a plurality of exposure times. The determination unit is configured to determine whether or not saturation occurs using at least one data item of a plurality of data items obtained during the plurality of exposure times. The illuminance calculation unit is configured to calculate, if the determination unit determines that the saturation occurs, an illuminance using a data item different from the at least one data item used in the determination.