The accuracy of an index indicating growth conditions of a crop obtained from a shot image is improved, while reducing the flight time of an aircraft shooting the crop. Crop image acquisition unit acquires an image of a crop region shot by drone. Index calculation unit calculates an index indicating growth conditions of a crop shot in the image based on the acquired image of the crop region. Flight instruction unit instructs, if a portion (low index region) regarding which the calculated index is less than a predetermined index threshold is present in the crop region, drone to shoot the low index region while increasing the resolution of the image. Specifically, flight instruction unit makes an instruction to shoot the portion while performing a low-altitude flight at an altitude lower than that when the image regarding which the index of the low index region has been calculated has been shot.