The present invention can achieve the reliability and simplicity in registering a fingerprint by indicating the quality of a fingerprint image by the number of pseudo minutiae, improve the security of an entrance/exit control system to register a fingerprint, detect the direction of ridge lines of a fingerprint accurately as much as possible, improve the security in checking a fingerprint remarkably, collect renewed registered fingerprint data by a host device and hold the registered fingerprint data of each gate as the latest fingerprint data, improve the operability by enabling to use identification numbers having the less number of digits, and register a fingerprint having a high match rate by automatically applying spatial filtering in re-registering only. A fingerprint registering method according to the present invention detects normal minutiae and pseudo minutiae in a fingerprint pictured by a fingerprint image pickup unit, counts pseudo minutiae in registering windows with normal minutiae at almost the center, determines the average number of pseudo minutiae in registering windows from a total of pseudo minutiae in all registering windows, and registers a fingerprint when the average number of pseudo minutiae is equal to or below a threshold.