PURPOSE: To maintain an oscillation even at a low flow rate by providing a means which alternately increases a pressure acting on a side flank of an obstructing part in connection with the oscillation of jet between wall parts in a fluidic oscillator having the obstructing part in a chamber including two wall parts crossing with a horizontal plane.

CONSTITUTION: The forward portion of an obstructing part 16 facing a nozzle 3 is formed in a V-shape, formed of two symmetrical wall parts 22 and 23, and crossed with a horizontal plane 2, and the wall part of the obstructing part 16 is passed by flow passages 11 and 12. When a jet is positioned at P2, it forms two vortexes. One vortex 31 is strong, the other one 32 weak. The flow passages 11 and 12 are positioned so that they correspond to those positions where the jet collides with the obstructing part 16 with the maximum deviation of jet from a symmetrical horizontal plane 2. At position P2, a part of fluid flows through the flow passage 12, flows out from a flow passage 15 to an outlet 13, and increases the pressure in a flow passage 5 and at an outlet 17 of the oscillator. The jet oscillates between two positions P1 and P2, and an oscillating frequency is in direct proportion to a flow rate. Thus, the minimum flow rate for oscillation can be increased.