Shipboard observations of cloud fraction were performed along the round-trip research cruise between Japan and Antarctica from November 2013 to April 2014 using both a whole-sky camera and a ceilometer onboard the Research Vessel (R/V) Shirase. Based on the results of the comparison of these cloud fractions, it was found that the correlation coefficient was 0.86 for the 2024 observations acquired between Australia and Antarctica from 27 November to 9 December 2013. Overall, the results were consistent between the two observation methods; however, some underestimation by the whole-sky camera was determined in comparison with the ceilometer. It is intended that shipboard observations will continue onboard the R/V Shirase over subsequent every years in order to improve the retrieval of cloud fractions for the validation of satellite observations.