A 3 μm bubble memory chip has been developed based on the established 6 μm bubble technology (1). As the saturation magnetization of 3 μm bubbles is nearly the same as that of 6 μm bubbles, propagation patterns are scaled down to 1/2 the size of those for 6 μm bubbles. However, the propagation of 3 μm bubbles in the H‐I pattern minor‐loops results in a remarkable increase in the minimum drive field, which is caused by anomalous bubble propagation. From the experimental study of the potential well depth under the H pattern, it is concluded that the anomalous propagation is caused by the magnetizing effect of bubbles on the patterns. This explanation can be justified by the fact that no anomalous propagation occurs when the H pattern is cut into two T patterns at its center. A 80‐kbit major‐minor memory chip was designed using broken H patterns. An overall operating margin of ∠8 Oe for a drive field of 40 Oe at 500 KHz was measured on a 282‐bit major‐minor loop chip with the same design.