| Official Name: | Somdet |
| Native Name: | สมเด็จ |
| Native Name Lang: | th |
| Settlement Type: | District |
| Subdivision Type: | Country |
| Subdivision Name: | Thailand |
| Subdivision Type1: | Province |
| Subdivision Name1: | Kalasin |
| Subdivision Type2: | Seat |
| Subdivision Name2: | Somdet |
| Subdivision Type3: | Subdistrict |
| Subdivision Type4: | Muban |
| Established Title: | District established |
| Population Total: | 51125 |
| Population As Of: | 2010 |
| Blank Name Sec1: | Postal code |
| Blank Info Sec1: | 46150 |
| Blank Name Sec2: | Geocode |
| Blank Info Sec2: | 4613 |
| Timezone: | ICT |
| Utc Offset: | +7 |
| Coordinates: | 16.7044°N 103.75°W |
Somdet (th|สมเด็จ, pronounced as /th/) is a district (amphoe) in the northeastern part of Kalasin province, northeastern Thailand.
Neighboring districts are (from the southeast clockwise): Huai Phueng, Na Mon, Mueang Kalasin, Sahatsakhan, and Kham Muang of Kalasin Province and Phu Phan of Sakon Nakhon province.
The minor district (king amphoe) Somdet was created on 16 August 1964, when the three tambons Somdet, Mu Mon, and Saeng Badan were split-off from Sahatsakhan district.[1] It was upgraded to a full district on 25 February 1969.[2]
The district is divided into eight sub-districts (tambons), which are further subdivided into 91 villages (mubans). Somdet is a township (thesaban tambon) which covers parts of the tambon Somdet. There are a further eight tambon administrative organizations (TAO).
| No. | Name | Thai name | Villages | Pop. | ||
|---|---|---|---|---|---|---|
| 1. | Somdet | สมเด็จ | 10 | 13,505 | ||
| 2. | Nong Waeng | หนองแวง | 16 | 9,774 | ||
| 3. | Saeng Badan | แซงบาดาล | 15 | 7,407 | ||
| 4. | Maha Chai | มหาไชย | 10 | 4,551 | ||
| 5. | Mu Mon | หมูม่น | 11 | 7,103 | ||
| 6. | Pha Sawoei | ผาเสวย | 11 | 7,555 | ||
| 7. | Si Somdet | ศรีสมเด็จ | 8 | 5,236 | ||
| 8. | Lam Huai Lua | ลำห้วยหลัว | 10 | 6,249 |