An infusion set for administration of fluid to a subcutaneous layer includes a cannula housing adapted for mounting onto a patient’s skin and a needle housing for connection to the cannula housing. The switching mechanism further comprises a switching lever swingably fitted to the base part. The apparatus adjusts the rotation positions of these other photosensitive drums to allow the phases of these other photosensitive bodies to be substantially matched to the phase of that given photosensitive body.