The state news agency MENA reported Monday that the church called its participation "futile" under the current makeup of the panel, dominated by Islamists.
Out of 100 committee members, only two were chosen from the church among six Christians.
Christians make up about 10 percent of Egypt's population. Most are Copts.
The Muslim Brotherhood's party and a smaller ultraconservative faction, which control the parliament, staked out a clear majority on the constitutional panel.
Some 25 public figures and liberals have pulled out of the body, saying it is fails to represent the country's diversity and does not have enough constitutional experts.