A computer controlled microchemical robot which carries out a series of chemical reaction steps in DNA sequence analysis of Maxam and Gilbert’s scheme is described. Within a 2‐h operation of this apparatus, one of the four types of solutions for G, A+C, C+T, or C analysis for a DNA restriction fragment is prepared and is ready for subsequent electrophoretic analysis. It is proven that the chemical robot operated by a computer command is capable of speedily accomplishing the fragmentation reaction for DNA sequencing with accuracy similar to that of a well‐trained technician.