| Tosu | |
| States: | China |
| Speakers: | few to none |
| Date: | 2012 |
| Familycolor: | Sino-Tibetan |
| Fam2: | Qiangic |
| Fam3: | Ersuic |
| Iso3: | none |
| Iso3comment: | included in [ers] |
| Linglist: | qob |
| Lingname: | (not ISO) |
| Glotto: | tosu1234 |
| Glottorefname: | Tosu |
Tosu (; autonym: pronounced as /do33ɕu33 na31/[1]) is a moribund Qiangic language of China which shows strong affiliations to both the Loloish languages and to Tangut, the language of the Western Xia. Yu (2012) classifies it as an Ersuic language, which belongs to the Qiangic branch. There are "almost no Tosu speakers left", or "practically" no Ersu speakers left.[2]
About 2,000 Tosu people live in Miǎnníng county and the villages around it, as well as in six outlying townships of that county, namely Hòushān (后山), Fùxīng (复兴), Huì’ān (惠安), Hāhā (哈哈), Línlǐ (林里), and Shābā town (沙坝镇).[3] Chirkova (2014) reports that it is spoken by more than 9 individuals, all in their seventies and eighties.