A 2:3 pulldown sequence detecting system includes a history data table that stores a correspondence between each input field and a determination result of whether each input field is a repeated field and a threshold value table that stores threshold values. The system compares pixels of each (or a first) field that forms an interlaced image with pixels of a third field one frame before the first field to calculate a difference absolute value, uses the threshold values to determine a distribution bias of the difference absolute value, detects, from the interlaced image, a repeated field candidate that occurs once in a five field cycle and fields other than the repeated field, and determines, based on a regularity of repeated field occurrence, whether each repeated field candidate is the repeated field. If any repeated field candidate is not the repeated field, the system controls the threshold values.