A magnetic bubble memory device is disclosed in which a hardened film made of a heat-resisting highly-polymerized organic resin and having a predetermined thickness is employed for an insulating film interposed between a conductor pattern and a soft magnetic material pattern. In a conventional magnetic bubble memory device in which the above-mentioned insulating film is made of SiO.sub.2, an abrupt step is produced in the soft magnetic material pattern due to the existence of the conductor pattern beneath a portion of the soft magnetic material pattern, and the margin of bias magnetic field is thereby lowered. According to the present invention, the step is reduced and smoothed, and thus the lowering of the margin can be prevented.