A bearing device includes a first bearing for a first roller; a second bearing for a second roller; a bearing holder for the first and second bearings, wherein when the first bearing is mounted in the holder, a peripheral surface of the first roller is projected out of the holder through an opening of the holder, and the second roller is provided in the second bearing contacting the first roller in the holder; a contact portion for determining a relative position between the first and second bearings by contacting the first bearing with the first bearing mounted in the holder; and a moving mechanism for moving the second bearing toward the opening with dismounting of the first bearing, and for holding the second bearing in a position in which at least a part of a peripheral surface of the second roller projects out of the holder through the opening.