The Chainat Highway District was established in 1941 and is under the jurisdiction of Highway Office 12 (Suphan Buri). The office building is located at kilometer 280+594 (left side) on Highway No. 1, Don Rang Nok - Hang Nam Nong Kham section, in Ban Kluai Subdistrict, Mueang Chainat District, Chainat Province. It occupies an area of ​​20 rai, 3 ngan, and 50 square meters. Currently, it is responsible for several highway routes. The total distance is 600.345 km (distance per 2 lanes).

The control is divided into 4 highway maintenance divisions:
1. Sapphaya Highway Depot
Located at km 120+625 on Highway No. 32, section Pho Nang Dam Out - Tha Chanuan,
in Hat Asa Subdistrict, Sapphaya District, Chainat Province. Control distance: 166.228 km (distance per 2 lanes).

2. Sankhaburi Highway Depot
Located at km 145+841 (right side) on Highway No. 340, section Sankhaburi Hospital - Chainat,
in Phraek Si Racha Subdistrict, Sankhaburi District, Chainat Province. Control distance: 134.451 km (distance per 2 lanes).

3. Chainat Highway Depot
Located at km 289+560 (Left side) Highway No. 1, Don Rang Nok - Hang Nam Nong Kham section,
located in Thamma Mun Subdistrict, Mueang District, Chainat Province. Controlled distance: 187.600 km (distance per 2 lanes).

4. Noenkham Highway Depot
Located at Km. 135+625, Highway No. 340, Pak Nam - Sankhaburi Hospital section,
located in Wang Kai Thuean Subdistrict, Hankha District, Chainat Province. Controlled distance: 122.776 km (distance per 2 lanes).