Mr Sutthipong forecast Thai arrivals in South Korea would decline further this year to 330,000, compared with 400,000 last year, the Pattaya Mail reported.
He said most of South Korea’s tourist attractions were suitable for a one-time visit and return trips by Thai travellers were low.
He also attributed the drop to Japan's new policy to waive visas for Thai tourists, adding that Japan was more diversified in terms of attractions.
Thai tourists, he said, viewed South Korea as a popular shopping destination with a limited range of other activities.
Mr Sutthipong said the lower tourist turnout also posed a risk to low-cost airlines operating between Thailand and South Korea.
At the moment, he said, Japan offered a more lucrative market for budget airline operators.