Abstract: A flow meter using digital signals constructed in a small size and outputting an electric signal of a position of a float in a tapered tube with high accuracy is provided. A first reflecting means 6 has a ray 20 entered from the entering means 5 and reflected, and a second reflecting means 7 reflecting the ray 20 reflected from the first reflecting means 6 toward the first reflecting means 6 at least once. An emitting means 8 has the ray 20 entered and emits it, and an image sensor 9 has the ray 20 from the emitting means 8 entered and outputs an image of the float 3 in the tapered tube 1, while a control portion executes input processing of an image and outputs an electric signal S1 indicating the flow rate of a fluid 2 by detecting the position of the float 3.