A thermoelectric conversion material having a high dimensionless figure of merit ZT includes: a large number of polycrystalline grains which include a skutterudite-type crystal structure containing Yb, Co, and Sb; and an intergranular layer which is between the neighboring polycrystalline grains and includes crystals in which an atomic ratio of O to Yb is more than 0.4 and less than 1.5. A method for manufacturing a thermoelectric conversion material includes: a weighing step; a mixing step; a ribbon preparation step by rapidly cooling and solidifying a melt of the raw materials by using a rapid liquid cooling solidifying method; a first heat treatment step including heat treating in an inert atmosphere with an adjusted oxygen concentration; a second heat treatment step including heat treating in a reducing atmosphere; and manufacturing the thermoelectric conversion material by a pressure sintering step in an inert atmosphere.