We developed a system for automatically sketching patterns on the surface of porcelain. The system consists of two parts – measurement for the three-dimensional (3-D) porcelain piece using slit lighting and automatic pattern sketching. Since we classified porcelain pieces into two types by shape, two 3-D measurements were developed. We propose calculating of 3-D coordinates simply and quickly. Sketching uses numerical control. Numerical control data for sketching patterns onto porcelain were generated using results measured by the measurement and CAD systems. Experimental results verified the system’s effectiveness.