A 324-MHz DTL accelerates beams from 3 to 50 MeV. It consists of three post-stabilized tanks. An accelerating field of 2.5 MV/m is determined from the viewpoints of satisfying the equipartitioning condition and being sufficiently low for avoiding any discharge problem. All drift tubes contain quadrupole magnets. Model magnets of the electroplating-coil type with a magnetic-field gradient of 117 T/m were designed and successfully fabricated.