According to the present disclosure, there is provided an exposure control device configured to acquire an image signal output from an imaging element; acquire a specific subject region in an image represented by the image signal; calculate a first exposure value of a set region that is set in the image and a second exposure value of the subject region; decide a first weight for the first exposure value and a second weight for the second exposure value based on first determination of determining importance of the subject region with respect to the set region and second determination of determining a positional relationship between the set region and the subject region; and calculate a third exposure value by performing weight addition on the first exposure value and the second exposure value using the first weight and the second weight.