Trials on the transmission of olfactory information together with audio/visual information are currently underway. However, a problem exists in that continuous emission of scent leaves scent in the air causing human olfactory adaptation. To resolve this problem, we aimed at minimizing the quantity of scent ejected using an ink-jet olfactory display developed. Following the development of a breath sensor for breath synchronization, we next developed an olfactory ejection system to present scent on each inspiration. We then measured human olfactory characteristics in order to determine the most suitable method for presenting scent on an inspiration. Experiments revealed that the intensity of scent perceived by the user was altered by differences in the presentation method even when the quantity of scent was unchanged. We present here a method of odor presentation that most effectively minimizes the ejection quantities.