According to one embodiment, a pattern characteristic detection apparatus for a photomask includes a detection-data creating portion, a reference-data creating portion, an extracting portion, a first area-setting portion, a detecting portion and an collecting portion. The detection-data creating portion is configured to create detection data on the basis of an optical image of a pattern formed on a photomask. The reference-data creating portion is configured to create reference data of the pattern. The extracting portion is configured to extract a pattern for pattern characteristic detection and positional information of the extracted pattern. The first area-setting portion is configured to set an area where pattern characteristics are to be detected, and configured to extract a target pattern. The detecting portion is configured to detect pattern characteristics of the target pattern within the area. In addition, the collecting portion is configured to collect the detected pattern characteristics.