A whirlpool bath with an inverter-controlled circulating pump (P) comprises a bathtub body (1), a circulating pump (P) driven by a power-operated motor (M), a hot water circulation path (D) disposed between the bathtub body (1) and the circulating pump (P), the hot water circulation path (D) comprising a hot water suction path (10) and a hot water forced-feed path (11), the hot water forced-feed path (11) having at least one terminal end which is open into the bathtub body (1), at least one injection nozzle (3) which is mounted on the terminal end of the hot water forced-feed path (11), an air intake portion (5) connected to the hot water forced-feed path (11) to permit blowing of bubbling hot water into the bathtub body (1) from the injection nozzles (3), an inverter (E) interposed between a drive circuit (C) of the power-operated motor (M) of the circulating pump (P) and a power source and an electricity insulation means protecting the transfer of high frequency components of inverter-produced current to the hot water in the bathtub body (1). Due to such construction, the circulating pump (P) can be controlled such that the revolution of the motor (M) is readily and smoothly varied by way of a frequency modulation effected by the inverter (E) to provide the injection of hot water in various modes which are different in the injection amount and pressure of the injected hot water, while assuring a maximum degree of safety of a bather.