1. An evaluation system that evaluates a search operation that detects a detection subject on an object by using a photoelectric conversion signal obtained by photoelectrically detecting an area to be detected that includes the detection subject, the system comprising: an obtaining unit that obtains results of detection of the detection subject that uses the photoelectric conversion signal by assuming that the detection subject is located at any potential position among a plurality of potential positions with the area to be detected; a specifying unit that specifies at least one potential position from among the plurality of potential positions, based on specifying information used to specify a potential position of the detection subject; a computing unit that, based on the results of detection obtained by the obtaining unit assuming that the detection subject is located in the at least one potential position specified by the specifying unit, obtains a plurality of characteristic amounts of the detection subject at the specified potential position, and based on the plurality of characteristic amounts, computes a degree of recognition of the detection subject; an analyzing unit that determines whether or not the detection subject can be recognized based on the degree of recognition computed by the computing unit and a threshold value set in advance, and in the case when the detection subject cannot be recognized, analyzes an error factor that affects the degree of recognition; and a display unit that displays the error factor analyzed by the analyzing unit, wherein the detection subject is one of a plurality of marks formed in the same or similar process on an object, the evaluation system further comprising: an estimating unit that estimates the specifying information, based on processing results of a statistical processing using position information of other marks on the object that exclude a mark serving as the detection subject included in the area to be detected.