
The fire started on the second floor of the building on Soi Pracha-uthit 27 on Pracha-uthit road at 6am.
Initially, it took about 15 minutes to control the blaze but it flared up again at 9am, prompting firefighters to go inside.
Police said the building was used to store guitars and ukuleles.
No injuries were reported. The cause and extent of the damage have yet to be established.