小孢癣菌（学名：Microsporum）是子囊菌门下的一属，与毛癣菌属、表皮癣菌属同为皮肤真菌，在皮肤及毛发造成皮肤感染。

小孢癣菌可产生大分生孢子（Macroconidia）及小分生孢子（microconidia），大分生孢子呈透明状、梭形且有隔板（septum），大小约为7-20乘30-160微米，并在细胞壁上有小刺或疣状突起，呈凹凸不平，这些特征也是鉴定物种差别的重要依据之一。小分生孢子也是透明的，呈棍状或梨形，表面光滑，大小约为2.5-3.5乘4-7微米，数量较大分生孢子为少。

小孢癣菌与毛癣菌分别的主要的依据是表面粗糙的大分生孢子，虽然这种特征有时较难观察。小孢癣菌属下已有17种物种被鉴定出。

Microsporum is a genus of fungi that causes tinea capitis, tinea corpus, ringworm, and other dermatophytoses (fungal infections of the skin). Microsporum forms both macroconidia (large ****ual reproductive structures) and microconidia (smaller ****ual reproductive structures) on short conidiophores. Macroconidia are hyaline, multiseptate, variable in form, fusiform, spindle-shaped to obovate, 7–20 by 30–160 um in size, with thin or thick echinulate to verrucose cell walls. Their shape, size and cell wall features are important characteristics for species identification. Microconidia are hyaline, single-celled, pyriform to clavate, smooth-walled, 2.5–3.5 by 4–7 um in size and are not diagnostic for any one species.