The approval of orphan anticancer drugs in Japan has increased to meet high social demand. Drug lag, namely the approval lag of new drugs, is recognized as a social issue in Japan. We investigated the approval lag and its components, submission lag and review-time lag, between Japan and the United States (US) to reveal whether an approval lag still exists, and to identify potential factors that may contribute to reducing the approval lag. Anticancer drugs approved in Japan between April 2004 and November 2017 were investigated using publicly available information. Results showed that the median approval lag of orphan anticancer drugs in 2016-2017 was 727.0 days (interquartile range, IQR, 310.0-1054.3). The approval lag was significantly correlated with the submission lag (correlation coefficient = 1.00, P < 0.001) but not with the review-time lag (correlation coefficient = -0.16, P = 0.22). The submission lag was significantly longer for orphan anticancer drugs than non-orphan drugs (median, 712.5 days [IQR, 186.0-1448.3] vs. 387.0 days [92.8-1096.0], P = 0.023). External collaboration in drug development was associated with a longer submission lag (coefficient = 762.1, P = 0.017), while breakthrough therapy designation in the US was associated with a shorter submission lag (coefficient = -832.8, P = 0.035). In conclusion, we revealed that an approval lag for orphan anticancer drugs still existed in 2016-2017. A submission lag for orphan anticancer drugs was the main component affecting the approval lag, and was longer than that for non-orphan drugs. External collaboration in drug development may be a potential factor in reducing the submission lag for orphan anticancer drugs.