Informal interaction at workplace plays a key role in job performance through variety of mechanisms, such as stress buffering, enhanced information sharing, enhanced trust, and so on. However, in previous literature, there is a dearth of empirical evidence on what type of informal interaction matters at workplace. Thus, this study conducted a population-based cross-sectional survey (N=8,169) to examine the relationships between positive or negative informal interaction at workplace and job performance, operationalized as work engagement, subjective job performance and job satisfaction. Hierarchical multiple regression analyses showed that positive informal interaction was statistically significantly associated with work engagement (β = .23, p < .001), subjective work performance (β = .23, p < .001), and job satisfaction (β = .13, p < .001), even after controlling for covariates. On the other hand, no such relationship was generally observed for negative informal interaction. Further understanding of the unique mechanism through which positive informal interaction, such as laugh at workplace, influences job performance is warranted for future research.