A face image processing method using a registration database in which face images of persons who are permitted in advance to enter a predetermined closed space and narrowing-down information corresponding to the face images are registered, the method comprising: acquiring narrowing-down information corresponding to at least one of a person entering and exiting the closed space; collating the narrowing-down information registered with the narrowing-down information to be acquired; and determining a search range of the face images registered in the registration database based on a collation result of the narrowing-down information registered and the narrowing-down information to be acquired, the search range being search targets used in authentication processing of the face image of at least one person entering and exiting an area provided inside the closed space, wherein the narrowing-down information registered is first identification information for identifying the persons who are permitted to enter the closed space in advance, the narrowing-down information to be acquired is second identification information for identifying at least one person entering and exiting the closed space, and the search range of the face images registered in the registration database is determined based on a collation result of the first identification information and the second identification information, the face image corresponding to the first identification information that matches the second identification information of the person who has entered the closed space is included in the search range, and the face image included in the search range is excluded from the search range in a case where exit from the closed space by the person who has entered the closed space is detected. acquiring narrowing-down information corresponding to at least one of a person entering and exiting the closed space; collating the narrowing-down information registered with the narrowing-down information to be acquired; and determining a search range of the face images registered in the registration database based on a collation result of the narrowing-down information registered and the narrowing-down information to be acquired, the search range being search targets used in authentication processing of the face image of at least one person entering and exiting an area provided inside the closed space, wherein the narrowing-down information registered is first identification information for identifying the persons who are permitted to enter the closed space in advance, the narrowing-down information to be acquired is second identification information for identifying at least one person entering and exiting the closed space, and the search range of the face images registered in the registration database is determined based on a collation result of the first identification information and the second identification information, the face image corresponding to the first identification information that matches the second identification information of the person who has entered the closed space is included in the search range, and the face image included in the search range is excluded from the search range in a case where exit from the closed space by the person who has entered the closed space is detected.