| Official Name: | So Phisai |
| Native Name: | โซ่พิสัย |
| Native Name Lang: | th |
| Settlement Type: | District |
| Subdivision Type: | Country |
| Subdivision Name: | Thailand |
| Subdivision Type1: | Province |
| Subdivision Name1: | Bueng Kan |
| Subdivision Type2: | Seat |
| Subdivision Name2: | So |
| Subdivision Type3: | Tambons |
| Subdivision Name3: | 7 |
| Subdivision Type4: | Mubans |
| Subdivision Name4: | 89 |
| Established Title: | District established |
| Established Date: | 1972 |
| Population Total: | 69450 |
| Population As Of: | 2010 |
| Blank Name Sec1: | Postal code |
| Blank Info Sec1: | 38170 |
| Blank Name Sec2: | Geocode |
| Blank Info Sec2: | 3803 |
| Timezone: | ICT |
| Utc Offset: | +7 |
| Coordinates: | 18.0783°N 103.4433°W |
So Phisai (Thai: โซ่พิสัย, in Thai pronounced as /sôː pʰí.sǎj/) is a district (amphoe) of Bueng Kan province, northeastern Thailand.
The minor district (king amphoe) So Phisai was established on 1 March 1972, when the three tambons So, Si Chomphu, and Nong Phan Tha were split off from Phon Phisai district.[1] It was upgraded to a full district on 13 April 1977.[2]
Neighboring districts are (from the west clockwise): Fao Rai and Rattanawapi of Nong Khai province; Pak Khat, Mueang Bueng Kan, and Phon Charoen of Bueng Kan Province; and Ban Muang of Sakon Nakhon province.
The district is divided into seven sub-districts (tambons), which are further subdivided into 89 villages (mubans). So Phisai is a sub-district municipality (thesaban tambon) which covers parts of tambon So. There are a further seven tambon administrative organizations (TAO).
| No. | Name | Villages | Thai | Pop.[3] | |
|---|---|---|---|---|---|
| 1. | So | โซ่ | 17 | 16,589 | |
| 2. | Nong Phan Tha | หนองพันทา | 11 | 8,659 | |
| 3. | Si Chomphu | ศรีชมภู | 15 | 12,165 | |
| 4. | Kham Kaeo | คำแก้ว | 13 | 9,576 | |
| 5. | Bua Tum | บัวตูม | 13 | 9,383 | |
| 6. | Tham Charoen | ถ้ำเจริญ | 11 | 7,757 | |
| 7. | Lao Thong | เหล่าทอง | 9 | 5,321 |