PURPOSE: To prevent such a case where magnetic bubbles are written in or read out of a defective minor loop with simple constitution, by short-circuiting the conductor of a functional part of the defective minor loop by a plating technique, etc.

CONSTITUTION: A through-hole 7 piercing through an insulated layer and a protecting layer is formed at the root of a conductor formed in a U-shape at the gate of each minor loop 10. The quality of the loop 10 is decided by a working test of a magnetic bubble memory element. The conductor 3 for gate of a nondefective loop 10 is patterned on the hole 7 by a photoresist in order to avoid the short circuit of said conductor 3. Then only the gate conductor of a defective loop is short-circuited. Such processing is applied to both the conductor for replicate gate 15 and the conductor for swapping gate 14. In such a case, no bubble enters a defective loop even though the bubble information is written mistakenly in the defective loop. Furthermore, the bubbles if put into the defective loop are never read out.