The present invention relates to an underwater health care bathtub for a person with back pain, which comprises: a bathtub unit； a lumbar block placed on the bottom unit of the bathtub unit in a long shape in order to support the lumbar of a user； and a low-frequency stimulator outputting low-frequency current to water in the bathtub unit. The lumbar block comprises: a block base placed at a fixed height along the longitudinal direction of the bathtub unit from the center of the bottom unit of the bathtub unit； and a cushion unit placed in the upper part of the block base to function as a cushion. The low-frequency stimulator comprises: a stimulator main body equipped with a controller for controlling current, voltage, and frequency, the CPU and a pulse generator, and including a display window, an operation mode display unit, and an output intensity regulation unit； a pair of electrode pads composed of a pad unit which is manufactured by a conductive rubber material in a plate shape, an adsorption plate which is to be attached to the wall surface of the bathtub, and a connection fixture which is integrated with the pad unit at the edge of the pad unit in order to connect the pad unit to the main body； and a lead wire connecting the stimulator main body and the electrode pads. Therefore, the underwater health care bathtub for a person with back pain can provide user convenience for a person with waste and neck pain by allowing the person to lay his/her waist on the bottom of a bathtub to comfortably lay his/her trunk, and can reduce pain by stimulating an inconvenient body part with low-frequency stimulus.본 발명에 따른 등 통증자용 수중헬스케어 욕조는, 욕조부； 욕조부의 바닥부에 길게 배치되며, 요추를 지지하도록 배치되는 요추 블록； 및 욕조부의 수중에 저주파 전류를 출력시키는 저주파 자극기를 포함하며, 요추 블록은 욕조부의 바닥부 중앙에서 욕조부의 길이 방향을 따라 일정 높이로 배치된 블록 베이스； 및 블록 베이스의 상부에 배치되며 쿠션 작용하는 쿠션부를 포함하며, 저주파 자극기는, 전류ㅇ전압ㅇ주파수를 제어하는 제어장치와 CPU 및 펄스발생기가 내장되며, 표시창과 작동모드 표시부 및 출력 강도 조절부가 구비된 자극기 본체； 전도성 고무 재질로 판상으로 제작된 패드부와, 욕조의 벽면에 부착시키기 위한 흡착판과, 패드부를 본체와 연결시키기 위해 패드부
