The present invention relates to a calendar display device, especially relates to a calendar display device for a mechanical watch piece, including: a first disk (1), the disk of days, carrying multiple series of inscriptions symbolizing the seven days of the week; a second disk (2), the disk of dates, carrying inscriptions symbolizing the date of the month; a third disk (3), the disk of months, carrying 12 inscriptions symbolizing the months of the year. One (1, 2) of the disk of days (1) and the disk of dates (2) acts as a dial by being fixed, whereas the other (2, 1) acts as a rotary disk by being arranged concentrically and rotatably in relation to the dial. The dial includes an aperture (2.1) making it possible to see the inscription of the current month on the disk of months (3) which is mounted rotatably and is driven, either directly or indirectly, by a watch movement of said watch piece; a hand (4) placed concentrically and rotatably in relation to said dial so as to indicate simultaneously a date and a day of the week; a direct kinematic link (7, 8) between the disk of months (3) and the rotary disk (1, 2) to realize automatic indexing between the inscriptions on the rotary disk (1, 2) and the inscriptions on the rotary disk (2, 1) according to the displayed month; and a correction mechanism (9, 10) comprising equipment configured to advance and reverse the disk of months (3) so as to allow modification of the month displayed on the dial (1, 2) in a bidirectional manner. The present invention also relates to a watch piece comprising the calendar display device.