No. – If you desire to go to Northern Ireland you will need a UK Visa. If you are roving to the Republic of Ireland, and you mean to also visit Northern Ireland and revisit to the Republic, you have to get a multiple-entry Irish visa and a UK visa. If your chief purpose is Northern Ireland although you arrive in, and head off from the Republic of Ireland, you have to first obtain a UK visa, and then a multi-entry Irish visa.