PURPOSE: To ensure the management of defective patterns easily, by eliminating a part of the transfer pattern and fixing data to the loop having deficiency in the minor loop mutually transferred with the major loop via the transfer gate.

CONSTITUTION: The magnetic bubbles are transferred mutually via the transfer gates T-1, T-2... between the major loop M.O and the minor loops m-1, m-2., and parallel write-in and read-out of data are made. The loop m-1 is assembled in the memory chip, a part of deficiency is regarded as perfect deficiency to the loop m-i having defect, and a part 22 of the pattern is removed. Then, the loop m-i is fixed to the data 0 at all times without being effected due to external environs. Accordingly, ahead the use of the magnetic bubble memory, the data 1 is transferred to the loop M.O, write-in is made to the loops m-1..., and when it is read out, the deficient loop can be identified surely without provision of the defection detective ROM by means of the data 0.