Thammamun Wora Wihan Temple has been respected by people in Chai Nat province since the Ayutthaya period. It is located on Thammamun hillside along the Chao Phraya River in Thammamun sub-district, about 2 km from Mueang district to the north along Highway 1 at 288th-289th kilometer markers. The entrance is at Thammanukun School.

Inside the vihara, there is an image of Luang Pho Thammachak in standing Buddha, with the gesture of forbidding the relatives from fighting each other on a lotus base. This image is the art from the late Chiang Saen period to early Sukhothai period mixed with the Ayutthaya period. Dharmachakra or wheel of Dhamma appears in the center of the right hand. It was assumed that the craftsmen that purposely put the Mahapusiralakkhana into the image (the characteristic of a great man according to ancient Indian tradition such as wheel on the sole, net pattern on the palm and sole, conch-shaped ankle, and chin like lion).

Another highlight in this temple is the stone boundary markers, which were made of red sand stones around the ordination hall. These stones were carved with Ayutthaya style. The Luang Pho Thammachak worship ceremony will be held twice every year on the 4th-8th of 6th lunar month and 4th-8th on 11th lunar month. As for Luang Pho Thammachak’s history, there is still no concrete evidence. It was only told from generations to generations that three Buddha images floated down the Chao Phraya River.

They are Luang Pho Sothon of Sothon Wora Wihan Temple in Chachoengsao province; Luang Pho Wat Ban Laem from Ban Laem Temple in Samut Songkhram province; and Luang Pho Thammachak of Thammamun Wora Wihan Temple in Chai Nat province. Some said another Buddha image that is Luang Pho Wat Rai Khing floated along the river. When they floated to the front of Thammamun Wora Wihan Temple, Luang Pho Thammachak stopped and floated around. Monks and local people did a ritual to enshrine the image up but it would not. That evening the image moved and blocked the entrance of the temple.

Therefore, the third part of the vihara was built. The image stayed in the vihara for three days then moved back to its original place with mud and duckweed. Local people chained the image so it will not move again. After that, a man from the other place travelled on a raft from the north down the river to find the lost Buddha image. When he reached Thammamun Wora Wihan Temple, he found his lost image. It was at dusk, so he decided to stay a night at the temple to wait for the morning to enshrine it to the original temple. That night he had a dream; Luang Pho did not want to go back. The next morning he said goodbye to the abbot and went back with the wheel from the image.

After this incident, the image did not move again. Local people had the chain removed and made a new wheel. The ceremony is held every year until now. So far, a lot of people have visited the temple and made merit here ceaselessly.