Abstract: In this study, a new application technique that is different from the existing hearing aid ear shell manufacturing method was experimented by combining a medical image and 3D printing. The surface precision of the ear shell shape was compared based on the medical image for application to the hearing aid manufacturing technique. The external auditory meatus shapes with different Digital Imaging and Communications in Medicine (DICOM) image thicknesses were manufactured based on 3D printing and the surface precision and the difference in the modeling structure were compared. The results of the experiment showed that the size of the external auditory meatus shape had a problem with the Z-axis shape size during 3D image acquisition. The shape surface roughnesses were 0.453, 0.872 and 1.187 μm for the 0.5, 1.0 and 2.0 mm image thicknesses, respectively, indicating that superior surface roughness was obtained as the image thickness decreased. For the converted STereoLithography (STL) modeling, the distribution of the face became denser as the DICOM image thickness of the shape decreased. As for the difference, the 1.0 mm image thickness showed a 31.7% increase and the 0.5 mm image thickness showed a 94.9% increase, compared to the Unigraphics 2.0 mm. The results of this study showed that for the manufacture of hearing aid ear shell based on the DICOM method, superior surface and shape precisions were obtained as the DICOM image thickness decreased.