The 2004 Cork Junior A Hurling Championship was the 107th staging of the Cork Junior A Hurling Championship since its establishment by the Cork County Board in 1895. The championship began on 17 October 2004 on 14 November 2004.
On 14 November 2004, Ballygarvan won the championship following a 3-7 to 1-12 defeat of Grenagh in the final. This was their first championship title in the grade.
Ballygarvan's Liam Dillon was the championship's top scorer with 1-33.