To provide a method for removing foreign matters such as wood waste from gravel by which waste such as wood waste can be surely removed without requiring a large facility with good working property and little amount of water.

A jetting apparatus of water or air is disposed under the drop port of gravel and water or air is horizontally jetted to the dropping gravel while a fixed amount of the gravel is concentratedly and continuously dropped through the drop port to blow off the waste such as wood waste mixed in the gravel into one direction to separate the waste from the gravel. Thus, waste such as wood waste can be surely removed without requiring a large facility with good working property and a relatively small amount power and water, and a ready-mixed concrete material of high quality can be rapidly obtained at a low cost.