Disclosed herein is a portable hydrogen-rich water generator that includes a separable drinking cup, an electrolytic cell which includes an anode, a cathode, a solid polymer electrolyte membrane, etc. and is disposed at the bottom of the drinking cup, a reservoir base on which the drinking cup is mounted and in which an anode reaction of the electrolytic cell is generated, a float valve which allows water to be continuously supplied at a certain water level from a water tank, and a power supply to apply direct current power to the electrolytic cell. In the portable hydrogen-rich water generator, when power is applied after putting purified water into the drinking cup and mounting the drinking cup on the reservoir base, the electrolytic cell electrolyzes the water in the reservoir base so that oxygen is generated at the anode of the reservoir base side and hydrogen is generated at the cathode of the drinking cup side, thereby allowing hydrogen gases to be dissolved in the purified water in the drinking cup within a short time with the consequence that hydrogen-rich water is produced.