Modern electron cyclotron resonance ion source (ECRIS)s are able to produce intense beams of highly charge positive ions, of which charge states are higher than those obtained from electron stripping at the high voltage terminal of tandem accelerators. It is possible to increase beam intensity, beam energy and beam species by utilizing an ECRIS in a tandem accelerator. A small permanent magnet ECRIS has been installed in the high voltage terminal of the vertical and folded type 20UR Pelletron tandem accelerator at Japan Atomic Energy Research Institute at Tokai. Acceleration tests have been successfully carried out with beams ofH+,N2+,O3+,5+,Ar6+,8+,9+and132Xe12+,13+ions. ©1999 American Institute of Physics.