PURPOSE: To improve the transfer characteristics, start, stop characteristics of a bubble and to simultaneously increase a detection output by a method wherein Hc of permalloy in a detector set to 10e or above while Hc of permalloy in a transfer path is set to 10e or below.

CONSTITUTION: 1 is a generator writing data, 2 is a swap gate transferring necessary data to a minor loop 3 and simultaneously discharging unnecessary data, 4 is a replicator splitting a bubble, and 5 is a detector detecting the bubble. Output (Sp-p) is increased as Hc is increased by setting Hc of permalloy at the parts except the detector 5 to 10e or below and by setting Hc of the permalloy at the part of the detector 5 only to 10e or above. Only detection output can be increased without deteriorating transfer characteristics, start, stop characteristics.