In an everyday life, we experienced and know that gum-chewing raises arousal, but this effect has not been proved experimentally. In the present experiment, it was examined using Japanese UMACL test. UMACL test (UWIST Mood-Adjective Checklist) is a self-reported questionnair, which was originally composed in English by Matthews, Jones and Chamberlain (1990). It consists of 3 dimensional-scales; Energetic Arousal (active-tired), Tense Arousal (nervous-calm) and Hedonic Tone (pleasure-displeasure). Fifty four undergraduate students were tested in class of psychology (December 8, 1992, 6: 00p.m.-7: 30p.m.). The UMACL test was performed twice; when the subjects were chewing gum, and they were not (for control). Gum chewing affected all the three UMACL scales significantly, in comparison to the control data. It raised Energetic Arousal. In Contrast, it Lowered Tense Arousal. It also raised Hedonic Tone. This pattern of results suggests that arousal effect from gum chewing is excellent and expedient.