Its members will also be balloted on industrial action unless the next UK government scraps a 1% pay-rise cap.
The Welsh Government, which sets pay for nurses in Wales, said the NHS Pay Review Body had recommended a 1% pay rise after looking at expert evidence.
The lowest earners will receiving a rise to the Living Wage, it added.
The RCN said a consultative ballot of its members in April showed a majority (78%) were prepared to go on strike, while 91% said they would support industrial action short of a strike.
About 52,000 of the 270,000 RCN members eligible to vote took part.
The union said the 1% cap on pay rises had left nursing staff with a 14% real terms pay cut since 2010 and it would launch a ballot on industrial action this year unless it was lifted.
A spokesman for the Welsh Government said: "We are proud of our nurses and we work to support them in Wales."
He said it offered NHS bursaries for eligible student nurses and supported professional development.
Some nurses in Wales are expected to join what the Royal College of Nursing (RCN) has described as a "summer of protest activity" over pay.