Even though it is not practical, yet there is a trend of the researches related to the anesthesia on the determination of depth of anesthesia and level of consciousness in the view point of neurophysiological aspects. That is, quantification of physiological signals which represent human brain function and pharmacological response could be used to find the level of consciousness based on the changes in physiological signals. This research was performed to analyze the relationship between parameters extracted from LAEP(long latency auditory evoked potential) and the amount of sedatives injected to the patients. Seventeen patients were participated for the experiment. Two different sedatives, midazolam and diazepam, were injected intramuscularly, and LAEPs caused by 1KHz and 2KHz auditory tone bust were obtained. It was found that amplitude of extracted parameters from LAEP, N100 and P300, were reduced as dose of sedatives were increased. Results of this study could be used for extracting more meaningful index and establishing algorithm for predicting changes of level of consciousness induced by sedatives.