In this article, published in Socio-Economic Review, my co-authors and I examine how supervisors’ gender relates to employees’ justice attitudes toward the earnings of men and women. We draw on data from two waves of a German employee panel study, conducted in 2012/2013 and 2017, to show that employees perceived higher earnings for men compared to women as fair. Exploiting our longitudinal research design, we find a change in gender bias in the justice evaluation of earnings for employees who experienced a change in supervisor gender: switching from a male to a female supervisor reduced the gender bias. This finding demonstrates that the workplace is an essential site for altering gendered beliefs about the fairness of earnings.