Fire is closely associated with human life. The purpose of this study was to use a probe stimulus/dual task methodology to investigate the psychophysiological effects of the fireplace. Participants made auditory discriminations during an "odd-ball task", while also looking at a lit fireplace. ERPs, button press performance, alpha power and questionnaire responses were measured or assessed. The amplitudes of the N2 components elicited by target and deviant stimuli were significantly decreased during later sessions. In contrast, there were no P3 component and reaction time to the target differences. Furthermore, alpha power increased through the sessions. Attention during the early stages of a trial was transfixed by the fireplace, as reflected in decreased N2 amplitudes. In addition, watching the fireplace appears to have induced relaxation, as indexed by increased alpha power. Real fire as a natural element may have some tranquil effects.Key words: fireplace, event-related brain potential (ERP), psychophysiology, tranquility ergonomicPeople often seek the tranquil effects of natural elements, in order to escape from a stressful society. They also positively like to insert some natural elements into indoor spaces (e.g., wood, flowers, natural sounds, and fire). Fire is closely related to human life. A genuine fireplace is relatively common in British and American homes, although this furnishing is very rare in Japanese homes (fireplace or wood stove presence = 39.0 % of British and 24.4% of American homes, versus 1.3% in Japanese homes) (Manago, 2004). Fireplaces serve a heating function but are also enjoyed for their psychological effects. Enjoying fire itself appears to be one reason to have a fireplace, in conjunction with being attractive interior accessories (Manago, 2004). A fire's psychological effects may contribute to an improved quality of life. There are few cognitive studies however, where a real-world material (such as fire) has been used as an experimental stimulus.Matsunami (2005) reported that a gas fireplace works to facilitate human communication. The distance between two participants who were strangers was smaller when sitting beside a working fireplace, compared to when no fireplace was present. Scores on a subjective scale in questionnaires measuring relaxation, healing, and familiarity were also higher in the presence of a fireplace.The main component of a fireplace is of course the flame itself. Researchers have used electroencephalogram (EEG) to measure the brain activity of participants watching a candle flame