Partial-label learning (PLL) is an important branch of weakly supervised learning where the single ground truth resides in a set of candidate labels, while the research rarely considers the label imbalance. A recent study for imbalanced PLL propose that the combinatorial challenge of partial-label learning and long-tail learning lies in matching between a decent marginal prior distribution with drawing the pseudo labels. However, even if the pseudo label matches the prior distribution, the tail classes will still be difficult to learn because the total weight of tail classes is too small. Therefore, we propose a pseudo-label regularization technique specially designed for imbalanced PLL. By punishing the pseudo labels of head classes, our method implements state-of-art under the standardized benchmarks compared to the previous PLL methods.