PURPOSE: To obtain a stable flowmeter strong against induction noise by bringing permanent magnets near to or away from a magnetic wire connected with a pickup coil, by the rotation of an impeller, and transmitting the generated pulse using a luminous element through a fiber cable.

CONSTITUTION: Permanent magnets 18aW18d are mounted on an impeller 12 within a tubular body 16 so that these magnets form magnetic poles in the same direction, and a magnetic wire 2 mounted with a pickup coil 26 and a resetting permanent magnet 28 are arranged within a casing 24 of a nonmagnetic material. This magnetic wire comprises a soft core 4, and a hard outer shell 6 having a coersive property and a reluctive force larger than those of the core 4. When the external field is eliminated, the outer shell retains a magnetism and tends to invert the external magnetic field in a direction opposite to the magnetized direction of the outer shell. At each time, each permanent magnet of the impeller draws near to the magnetic wire by the shift of a fluid, a pulse voltage is produced in the pickup coil, and hence, luminescence of a luminous element 30 is transmitted to the receiving side through a fiber cable 32, whereby it is possible to obtain a stable flowmeter strong against induction noise.