A current stretch detection method for a bubble device in which bubbles are written at least one bit apart. A stretch pulse is applied to a stretch conductor so that when a bubble is detected, it is maintained stretched, even though the bubble following it has moved one bit. Preferably the stretch pulse is of a convex-shape. A bubble device has a hairpin stretch conductor and a detecting element disposed centrally in the conductor. The terminal of the detecting element on the higher potential side is arranged so that it does not cross the stretch conductor. The contiguous propagation pattern is provided with a notch at a position in which the stretch conductor is located.