A method for producing low-carbon ferromanganese capable of achieving a high Mn yield. In producing low-carbon ferromanganese by blowing an oxidizing gas from a top-blowing lance onto a bath face of high-carbon ferromanganese molten metal accommodated in a reaction vessel provided with a top-blowing lance and bottom-blowing tuyere to perform decarburization, the slag composition during the blowing is adjusted so that a value of (CaO+MgO)/(Al.sub.2O.sub.3+SiO.sub.2) on a mass basis in the slag composition is not less than 0.4 but not more than 5.0. Also, agitation is performed under a condition that an agitation power density of an agitation gas blown through the bottom-blowing tuyere is not less than 500 W/t.