A printer including: a first printhead and a second printhead configured to eject ink to a print medium; a conveyance mechanism configured to convey the print medium; a camera configured to photograph the print medium; a carriage configured to carry and move the first printhead, the second printhead, and the camera; and a processor configured to print a third mark by the first printhead, photograph the third mark by the camera, adjust driving the conveyance mechanism and the carriage based on a result of the photograph, print a first mark and a second mark by the first printhead and the second printhead respectively, photograph the first mark and the second mark by the camera, and based on the result of the photograph, adjust the ink ejection timing of the second printhead.