PURPOSE:To improve the performance of relieving an element having a defective loop, by using an adjacent perfect loop as a reference position information storage loop when the reference position information storage loop is defective. CONSTITUTION:When the 1st minor loop 31 is defective and the 2nd minor loop 20' is perfect, the 2nd loop substitutes a reference position information loop automatically. Then, a 0 is stored in the area of an ROM correspondig to the minor loop 31 and although the minor loop 20' substituting the reference position information storage loop is perfect, a 0 is also stored in the area of the ROM corresponding to it. In the area of the ROM corresponding to another perfect minor loop 20, a 1 is stored. Thus, defective loop processing is carried out in normal operation to store reference position information without using the minor loop 20'.