It goes without saying that reliable and referable results will come from the standardized hearing tests. But standardizing tests of hearing is a difficult problem, especially in the hearing by bone conduction. Why so difficult is it in the bone conduction audiometry ? Thhere are two reasons. At first, bone conduction audiometry has more factors to be thought about in testing instruments and manipulations, for example, touching pressure of the receiver and so on. Next, the value which should be considered normal threshold fluctuates on rather wider range by bone conduction comparing with air conduction. Then, the following points are investigated in this report, i.e., "relations between the touching pressure of the receiver and the bone conduction threshold," "suitable masking noise" and "comparison of tests using continuous tone and interrupted tone." The ressults obtained are as follows: 1. As the touching pressure increases, bone conduction threshole goes down till it holds constancy. Generally speaking, the value of suitable pressure is 700g/㎠. 2. Necessary and tolerant masking noises have to be settled with one ear deaf patients and healthy men. But actual value of masking noise is to be varied in each case and in each instrument. 3. The threshold by interrupted test tone is lower than that by continuous tone. And the use of interrupted tone has many conveniences in practice.