Patent ID: 8864059

Claim:
A printing device comprising: a first roller that rotatably retains a roll body where a medium is rolled; a first motor that rotates the first roller; a second roller that is installed downstream of the roll body in a feeding direction of the medium to feed the medium in the feeding direction or in a reverse feeding direction which is opposite to the feeding direction; a second motor that rotates the second roller; and a controller that causes the medium to become slack between the first roller and the second roller by feeding the medium by a predetermined feeding amount in the reverse feeding direction by the second motor while keeping the first roller stationary such that the medium is intentionally slackened between the first roller and the second roller, and then rotates the roll body in a winding-up direction by the first motor while keeping the second roller stationary so that the slack between the first roller and the second roller is resolved to calculate a diameter of the roll body based on the rotation amount of the first roller at that time and the predetermined feeding amount.