Abstract: an image printing device comprises a transfer roller configured to transfer a printing medium in a transfer direction, a first sensor configured to detect a rotation amount of the transfer roller, a carriage mounted with a printhead. The image printing device further comprises a second sensor mounted to the carriage and configured to detect the printing medium. The image printing device further comprises a reference member disposed at a position opposing to the second sensor and a drive transmission mechanism configured to move the reference member in conjunction with a rotation of the transfer roller. The image printing device determines a position of an origin of the transfer roller based on detection results of the first sensor and the second sensor.