DENKAI is a set of computer program to calculate the 2-dimensional electrostatic field with cylindrical symmetry. Using simple commands, triangle meshes are automatically generated in MESH GENERATOR routine. The bandwidth of the coefficient matrix is reduced in the BAND WIDTH routine. The Laplace equation of the electrostatic field is solved in FIELD routine by inverting the coefficient matrix using Gauss method. The electric field lines are plotted by the FIELD PLOT routine, and the electric field intensities on arbitrary boundary can be read out by the FIELD LIST routine. (author).