A simple apparatus made by strain meter for measuring flow velocity. The main purpose of this design is to measure flow speed in ocean or river. This new flow velocimeter can vary the direction with sea current automatically and also can be placed under water for longer time without malfunction. This new flow velocimeter includes a free spin long cylinder vehicle which can drift in fluid and change direction according to the flow of fluid and the front-end toward the flow all the time. DC power is supplied from outside, hence the flow velocimeter can be put in fluid for long-term.