Abstract: A fluid jet flow massaging apparatus adapted for use within a bathtub unit comprises a first bathtub and a second bathtub which is accommodated within the first bathtub with a space defined therebetween and which has an inner volume sufficient for accommodating a person. The second bathtub is provided with opposed side walls within which a plurality of fluid circulation holes are formed and a fluid jet circulation flow generating device is disposed within at least one hole of at least one wall of the second bathtub. The fluid jet flow caused by the device is circulated through the holes and the space defined between the first and second bathtubs and the fluid jet flow achieves the massaging operation upon the person disposed within the second bathtub as a result of the circulation of the fluid. The fluid flow direction and the fluid flow rate may be regulated by altering the number of fluid flow generating devices.