Figures show recruitment to secondary school teacher training courses was more than a third below the target for the second year in a row.
The chief executive of the Education Workforce Councils said a national campaign to attract more people to the profession is needed.
The Welsh Government said the teacher vacancy rate is "comparatively low".
Wales' three teacher training centres recruited 538 students to secondary school teacher training courses, starting in September 2016, Higher Education Funding Council for Wales figures show.
This represents a 38% shortfall on the target of filling 871 places, following a 37% shortfall in 2015-16.