The fire in the three-floor building, which took about an hour to bring under control, caused damage initially estimated at B1 million.
The owner of the shop, Panida Mektawornsawas, 25, saw smoke when she was opening up, and promptly called for help.
Three fire trucks raced from Srisoonthorn Municipality Fire Station and other neighbouring stations to tackle the blaze.
Although the fire is believed to be the result of an electrical short, fire officers will investigate further to pin down the cause precisely.