Cork Senator Jerry Buttimer also attended the event and issued an apology on Twitter describing it as a "lapse of judgement"
He went to an Oireachtas golf event at a hotel in Galway on Wednesday attended by 80 others.
The Taoiseach has accepted his resignation and says it was wrong and an error of judgement.
Michael Martin also believes the event should not have gone ahead.
Minister Calleary says his attendance has undermined the government's efforts to tackle Covid 19.
Cork Senator Jerry Buttimer also attended the event and issued an apology on Twitter describing it as a "lapse of judgement" it's understood that at least three other senators attended the event, along with a number of former senators, a sitting TD, EU Commissioner Phil Hogan and a Judge
Education Minister and Fianna Fail colleague Norma Foley says Minister Dara Callery accepted what he did was wrong:
