A thoracic diagnosis assistance information generation method comprising: capturing a dynamic state of a chest portion including at least one breathing cycle using a detector with detecting elements aligned two dimensionally to generate a plurality of successive frame images; extracting a lung field region from one frame image among the plurality of frame images generated in the capturing; calculating air velocity by dividing the lung field region extracted in the extracting into a plurality of small regions, corresponding the small regions among the plurality of frame images, performing analysis for each corresponded small region, and calculating a feature amount showing air velocity for each small region; and calculating air velocity distribution by dividing the lung field region into a plurality of block regions in a trunk axis direction, calculating a feature amount showing air velocity of each block region based on a feature amount showing the air velocity of the plurality of small regions included in the divided block regions, and calculating a feature amount showing air velocity distribution of the lung field region in the trunk axis direction based on the calculated feature amount showing the air velocity of each block region, wherein calculating the air velocity distribution includes reading from a storage section a template showing air velocity distribution of a normal lung field and calculating as a feature amount showing air velocity distribution of the lung field region in the trunk axis direction, a degree of match of air velocity distribution between the lung field region and a lung field region in the template, based on a feature amount showing air velocity of the plurality of block regions and a feature amount showing air velocity in each corresponding region in the template, and wherein the calculating of the air velocity distribution includes calculating cross-correlation coefficient of the lung field region and the lung field region of the template as the degree of match of the air velocity distribution between the lung field region and the lung field region of the template. capturing a dynamic state of a chest portion including at least one breathing cycle using a detector with detecting elements aligned two dimensionally to generate a plurality of successive frame images; extracting a lung field region from one frame image among the plurality of frame images generated in the capturing; calculating air velocity by dividing the lung field region extracted in the extracting into a plurality of small regions, corresponding the small regions among the plurality of frame images, performing analysis for each corresponded small region, and calculating a feature amount showing air velocity for each small region; and calculating air velocity distribution by dividing the lung field region into a plurality of block regions in a trunk axis direction, calculating a feature amount showing air velocity of each block region based on a feature amount showing the air velocity of the plurality of small regions included in the divided block regions, and calculating a feature amount showing air velocity distribution of the lung field region in the trunk axis direction based on the calculated feature amount showing the air velocity of each block region, wherein calculating the air velocity distribution includes reading from a storage section a template showing air velocity distribution of a normal lung field and calculating as a feature amount showing air velocity distribution of the lung field region in the trunk axis direction, a degree of match of air velocity distribution between the lung field region and a lung field region in the template, based on a feature amount showing air velocity of the plurality of block regions and a feature amount showing air velocity in each corresponding region in the template, and wherein the calculating of the air velocity distribution includes calculating cross-correlation coefficient of the lung field region and the lung field region of the template as the degree of match of the air velocity distribution between the lung field region and the lung field region of the template.