A similar case search apparatus includes: a keyword extracting unit which extracts a keyword from an image interpretation report; a diagnosis tree analyzing unit which extracts, based on the keyword, one or more target diagnosis flows corresponding to the image interpretation report, by referring to a diagnosis tree storage unit storing diagnosis trees; a similar diagnosis flow extracting unit which extracts one or more diagnosis flows similar to the one or more target diagnosis flows from among the plurality of diagnosis flows included in the diagnosis trees stored in the diagnosis tree storage unit, based on the degree of difficulty regarding a diagnosis item or the degree of difficulty regarding a disease name; and a similar case searching unit which searches out one or more case data sets corresponding to the similar diagnosis flows from among a plurality of case data sets stored in a case data storage unit.