A magnetic bubble memory device according to this invention comprises a plurality of minor loops, a read-out major line is disposed at one end of the minor loops through gates having a replicating function, and a magnetic bubble detector which includes a detecting line is disposed at one end of the major line. Further, a propagation length from the other end of the read-out major line to the detecting line of the magnetic bubble detector is set at a bit length which slightly exceeds four times the number of the minor loops. For this reason, a continuous read-out operation at high speed is permitted without the influence of replicate pulses.