An error of an outline point due to a brightness fluctuation cannot be corrected by a simple method such as a method of adding a certain amount of offset. However, in recent years as the miniaturization of the pattern represented by a resist pattern has progressed, it has been difficult to appropriately determine a region that serves as a reference. An outline of the resist pattern is extracted from an image of the resist pattern obtained by a charged particle beam apparatus in consideration of influence of the brightness fluctuation. That is, a plurality of brightness profiles in the vicinity of edge points configuring the outline are obtained and an evaluation value of a shape of the brightness profile in the vicinity of a specific edge is obtained based on the plurality of brightness profiles, and the outline of a specific edge point is corrected, based on the evaluation value.