Kamalasai (, ; , ) is a district (amphoe) in the southern part of Kalasin province, northeastern Thailand.
Kamalasai is the location of the ancient city Mueang Fa Daet Song Yang. At present, only the remains of bricks mixed with soil. There is a two-story moat looks like a waterbody. Dvaravati oval-shaped city plan with a two-story city believed to be caused by urban expansion. There were excavated 130 Bai sema sandstones registered with the Fine Arts Department. In addition, it is also the location of Phra That Yaku, a local biggest chedi in the Dvaravati period during the 7thâÂÂ11th centuries.
The name Kamalasai means "lotus flower".
Neighboring districts are (from the west clockwise): Khong Chai, Mueang Kalasin, Don Chan of Kalasin Province, Pho Chai of Roi Et province, Rong Kham of Kalasin Province, and Changhan of Roi Et province.
Kamalasai is divided into eight sub-districts (tambons), which are further subdivided into 111 administrative villages (mubans).
<small>Missing numbers are tambon which now form Khong Chai District.</small>
There are five sub-district municipalities (thesaban tambons) in the district:
There are five sub-district administrative organizations (SAO) in the district: