Conch shell on the pedestal tray in the pavilion under the Cordia dichotoma tree. The seal was created from the history of Phra Nakhon Si Ayutthaya Province establishment. According to the narrative, there was the outbreak of cholera in 1347 that caused lot of death. King U-Thong evacuated people from the city to relocate at Nong Sano District, surrounded with rivers. During the settlement, establishing the shrines, performing religious ceremony, improving landscape for building the palace, the conch shell was found under the Cordia dichotoma tree. King U-Thong was very glad and, finally, built the small pavilion to place the conch shell.

Rectangular flag divided into 3 equal strips with two colors, blue strip in the middle and dark blue, which is the reginal color, on two sides. In the center of the middle blue strip, there is the seal of Phra Nakhon Si Ayutthaya Province, the conch shell pavilion under the Cordia dichotoma tree. There is the word "Ayutthaya" under the pavilion. The flag pole has two yellow and blue strips.