A first object of the present invention is to provide a surface-modified inorganic nitride having excellent dispersibility. Furthermore, a second object of the present invention is to provide a composition, a thermally conductive material, and a device with a thermally conductive layer which contain the surface-modified inorganic nitride.The surface-modified inorganic nitride of the present invention includes an inorganic nitride, and a compound which is represented by General Formula (I) and is adsorbed onto a surface of the inorganic nitride. In General Formula (1), n represents an integer of 3 or greater. X represents an aromatic hydrocarbon ring group or an aromatic heterocyclic group. Y represents a single bond, —O—, —CO—, —CO—O—, —O—CO—, —S—, —CS—, —NRA—, —N═N—, or a divalent unsaturated hydrocarbon group. RA represents a hydrogen atom or an alkyl group. R1 and R2 each independently represent a substituent. Here, at least one of R1 or R2 represents a monovalent organic group containing a specific functional group selected from the group A of specific functional groups.In General Formula (1), a plurality of X's may be the same as or different from each other. Moreover, a plurality of Y's may be the same as or different from each other.