[en] Alanine dosimeters of rod type (5 mmπx10 mm) were manufactured using polyethylene as a binder and their dosimetric properties were studied. It was found that when a dosimeter-element was set at the measuring position of an ESR apparatus of the inner modulation magnetic field type, and was rotated around its axis, the ESR response varied by a few percent, possibly caused by the ununiformity of alanine distribution in the element. Such variation of response is called 'orientation effect'. A method of reducing the orientation effect was studied experimentally, taking into consideration that the orientation effect approximately obeys sine function. It was confirmed that the method is effective enough to reduce the variation coefficient to the extent of within 1% for the ESR responses from uniformly irradiated dosimeter elements of the same lot. (author)