Sports have the power to fascinate people, and emotions are considered one of the key factors underlying this appeal. This study examined the extent to which emotional contagion occurs when viewers watch a medal-winning scene in a track and field relay event. To assess emotional contagion, participants were asked to rate their own emotional states in terms of four affective dimensions—high-arousal positive, low-arousal positive, low-arousal negative, and high-arousal negative emotions—based on the scale developed by Ito et al. (2018). They then estimated the athletes' emotional states using the same scale. A higher correlation between these two sets of scores was interpreted as a stronger indication of emotional contagion. Participants' general susceptibility to emotional contagion was also assessed using the Emotion Contagion Scale (Doherty, 1997), and the results suggested that individuals who are generally more susceptible to others' emotions also tend to experience stronger emotional contagion during sports spectating. Furthermore, the cues—facial expressions, attitudes, or behaviors—that participants referred to when estimating the athletes' emotions were also examined. The results provided insights into the conditions under which emotional contagion occurs during sports spectating. These findings indicate that this method can serve as an effective approach for identifying emotional contagion phenomena in real sports contexts. Based on these results, future research will investigate how emotional contagion among teammates influences team performance in group sports.