The present invention addresses the problem of charging a fiber sheet with charge at a high density to provide an electret fiber sheet with excellent dust-collecting properties. This electret fiber sheet is an electret fiber sheet wherein the relationship between a* and b* measured by a spectrocolorimeter when a red positively chargeable toner and a blue negatively chargeable toner are adhered thereon satisfies the expression [12<={-(b*)-(a*)}Ave<=50].