The performance of the RNB linac has been tested at KEK-Tanashi. The linac comprises a 25.5-MHz split coaxial RFQ and a 51-MHz interdigital-H (IH) linac. The test results are as follows: 1) the transmission of the RFQ is higher than 90% and that of the IH is nearly 100%, 2) the RFQ can accelerate ions with a charge-to-mass ratio from 1/2 to 1/30, 3) the IH can continuously vary the output energy in the range from 0.17 to 1.05 MeV/u, 4) the measured 2-rms 90% energy spreads are less than 2.4%, 5) the transmission for a Ne beam is about 80% and 6) the rf phase stability is within ±0.2°.