A method of cutting a recording medium for an ink jet device, the ink jet device including: a recording medium conveying unit that conveys a recording medium; and a full-line ink jet head that has substantially the same length as the width of the recording medium, and that ejects an ink toward the recording medium conveyed by the recording medium conveying unit according to image signal to effect recording, which includes: making a mark indicating the longitudinal position of the recording medium from the end head of the full-line ink jet head on the edge of the recording medium; and cutting the recording medium subjected to recording using the marking.