The move follows a spike in demand for face masks following a new outbreak of Covid-19.
Commerce officials on Wednesday visited a total of 573 pharmacies, shops and convenience stores but found no violations. Masks there were being sold for Bt2.50 apiece, or Bt50-Bt125 per pack of 50 depending on brand and quality.
Officials also found no evidence of hoarding. However, some shops were running short of face mask supplies due to the rising demand.
Boonyarit said there was no need to panic-buy or hoard masks, adding that supplies in Samut Sakhon where the latest outbreak emerged were still sufficient despite a spike in demand.
Thailand has 30 surgical face-mask factories capable of producing a total of 5 million masks per day.