The four-term MLA for Battle River-Wainwright says he is quitting immediately because it's time for fresh faces in the legislature.
Griffiths was a one-time municipal affairs minister and was a candidate in the 2011 Tory leadership race won by Alison Redford.
Fellow PC MLA Mary Anne Jablonski has also announced she will not run in the next election, that could come as early as this spring.
Jablonski is a five-term legislature member for Red Deer-North.
Former Wildrose MLA Joe Anglin has announced he will run for the PC nomination in the constituency of Rimbey-Rocky Mountain House-Sundre.
Anglin has been sitting as an Independent since he fell out with the Wildrose party last fall.