Disclosed is a novel NASH marker for use in a method for detecting NASH or evaluating the severity of NASH, which utilizes at least one factor selected from the group consisting of an IL-1 receptor antagonist, sCD40, HMGB1, sPLA2 group IIA and an sPLA2 activity as the marker. Also disclosed is a method for detecting NASH or evaluating the severity of NASH in a subject, which utilizes the marker.