A developing device includes a developer bearing body disposed in opposition to a latent image bearing body for bearing a latent image thereon. The developer bearing body develops the latent image using a developer. The developer has a degree of circularity greater than or equals to 0.93. The developing device further includes a developer layer forming member that contacts the developer on the developer bearing body to thereby form a developer layer. The developer bearing body rotates at a circumferential speed within a range from 185 mm/sec to 250 mm/sec. The initial fluidity of the developer is greater than or equals to 80%, and the tapping density of the developer is less than or equals to 35%.