Calendar mechanism and timepiece having the same

A calendar mechanism comprising:

• a month cam equipped with a cam surface distinguishing between a long month having 31 days and a short month having 30 days or less and adapted to make one rotation a year;
• a date indicator equipped with a date wheel and a month end tooth;
• a date indicator driving wheel equipped with a date finger adapted to make one rotation every 24 hours and engaged with the date wheel of the date indicator to rotate the date indicator;
• and
• an operating lever structure whose proximal portion is friction-engaged with an offset shaft so as to be capable of rotating around the offset shaft offset with respect to the rotation center of the date indicator driving wheel and which is equipped with a first distal end portion constituting a cam follower engaged with the month cam and a second distal end portion constituting a short month end feeding finger engaged with the month end tooth of the date indicator to effect additional date feeding by one day with respect to the date indicator at the end of a short month.