The influence of shapes and sizes of toner particles on electrophotographic image quality was studied, using a high-resolution laser beam printer. Six kinds of toners with different particle shapes and sizes were prepared in this study—two irregular, two quasispherical, and two spherical. All the toners were charged at almost the same values of q/m by mixing with ferrite carriers. An electrostatic latent image on the photoreceptor of the laser beam printer was developed by the dual-component magnetic brush development method. Images, both as developed on the photoreceptor before the transfer and fixed on the recording medium, were evaluated by optical microscopy. Effects of toner particle size and shape on as-developed images on the photoreceptor and on fixed images on the recording medium were studied. The quality of fixed images on the recording medium depended on both the shape and the size of the toner particle. Results were confirmed by the measurement of MTF of the fixed images on the recording medium. It was concluded that toner size plays an important role in as-developed images on the photoreceptor and that toner shape is further important for the final images. It is suggested that high-quality images are made by optimizing the combination of toner particle size and shape and electrophotographic process parameters.