A printer that conveys label paper or black mark paper executes an appropriate process when conveying paper that has been spliced. While conveying label paper or black mark paper by the conveyance unit 42, the inkjet printer 5 calculates the interval at which the labels or marks are disposed based on detecting the label edges or marks by a sensor disposed to the conveyance path. An error is detected if the calculated interval is shorter than a specified length. If the calculated interval is longer than the specified length, the calculated interval is compared with the previously calculated interval. If the previously calculated interval is the same as the specified length, an error is not detected. If the previously calculated interval is longer than the specified length, an error is detected.