Schools strike: Teacher quits over more work and not enough pay
"I think teachers are fed up that they can't, with what they have, do a proper job."
Tomi Rowlands is leaving his teaching job in Machynlleth, Powys, in April.
He said colleagues at Ysgol Bro Hyddgen faced heavy workloads and needed food banks to get by.
Thousands of National Education Union members were striking on Wednesday in the first of four walkouts over salaries and school budgets.
About a third of Wales' 1,500 schools were believed to have shut.
The Welsh government said it would continue "constructive" meetings with unions to try to resolve the dispute.