PURPOSE:To improve an S/N ratio and to obtain the device having excellent vibration resistance and rigid structure, in the device for measuring the flow speed and flow rate utilizing K arm an vortex, by mechanically separating a vortex generating body and shaft, and detecting respective stresses. CONSTITUTION:A stress detecting part 3a has a shape whose central part is blanked as shown in Figure B, and provided in the vicinity of a part where signal moment is maximum. A numeral 5 is a shaft which is inserted into a concave part 22 of the vortex generating body 2a with a gap 51 provided. One end of the shaft is supported 52 by the vortex generating body 2, and the other end is fixed to a pipe 1. Therefore, when the fluid under test flows in the pipe 1 and the arm an vortex is generated, bending moment acts on the vortex generating body 2a by the vortex lift, but it does not act on the shaft 5 and the bending moment becomes zero. Since the stress detecting part 3a, which measures the vortex signal, can be arbitrarily placed at the position where the stress is large, the large detected signal can be obtained.