The preparation of resting cells is one of the most important and most fundamental procedures for the physiological studies on bacteria. In order to know how we should do to get the resting cells suitable to the purposes of experiments, the author studied the influence of washing and suspending on the respiratory activity of bacteria. The results are summarized as follows: 1) For the purpose to obtain the resting cells of high respiratory activity, washing with phosphate buffer is better than that with distilied water or physiological saline solution. 2) When the prepared resting cells are used in a short time after the preparation, the respiratory activity is the same regardless of the sorts of the suspending solutions, distilled water, saline solution and phosphate buffer. 3) Borate and phthalate buffers of high concentration somewhat inhibit the respiration. However, in order to make the shift of pH less, M/15 (final concentration) is good. Phosphate buffer, even of M/15, does not inhibit the respiration. 4) In borate or phthalate buffers, the fall of respiratory activity is diminished by the addition of small amount of phospate.