Trap centers in amorphous silicon nitride (a‐SiNx) have been considered to be amphoteric. We found two signals of Si33/4 Si0and N33/4 Si0(Si dangling bonds with an unpaired electron) by an electron‐spin‐resonance method, and estimated the hole trap density to be larger than the electron trap density by about one decade, using the nonvolatile memory devices. As a result, we propose a new portrayal in which electron/hole traps are at the interface between Si clusters anda‐SiNxbulk, and hole traps are at nitrogen vacancies ina‐SiNxbulk.