Defects in lithium vanadate (Li3VO4) exposed to x rays were studied by electron spin resonance (ESR). 77 K irradiation produces two types of trapped‐hole centers. One is supposed to be carbonate radical CO3-, which is thermally stable even at room temperature. Another, having a hyperfine interaction with a vanadium nucleus (I=7/2, 99.76% natural abundant) is attributable to an intrinsic O- type center with one neighboring vanadium ion. The center is thermally unstable and anneals out around 200 K. In spite of the prominent detection of trapped‐hole centers, ESR signals due to trapped‐electron centers have not been clearly observed.