A throttle valve (10), in particular for injecting a fluid into a geological formation, is described, which comprises a valve body (10) having a piston chamber (11), an annular piston (20) having a fluid channel (21), which extends from a high-pressure side (H) to a low-pressure side (L) of the throttle valve, with the annular piston (20) being displaceable within the piston chamber (11) and the fluid channel (21) being transmissive or closed depending on the position of the annular piston (20) in the piston chamber (11), and a cover plate (12) which is provided on the high-pressure side of the valve body (10) and through which the fluid channel (21) protrudes from the high-pressure side piston chamber (11), wherein the fluid channel (21) is closed in axial direction with a sealing disk (22) which can be rested tightly on the cover plate (12) on the high-pressure side, and the fluid channel (21) has a radial throttle opening (23) adjacent to the sealing disk (22). A fluid injection device having such a throttle valve is also described.