After Japan’s colonization of Korea in 1910, many Korean peasants lost their land owing to the changes imposed in agriculture, and several Japanese coalmining companies started to recruit them as a colonial surplus population. Despite the low wages they offered, not all of the companies relied on Korean miners – the distribution of this workforce was strikingly uneven. Focusing on the mines of Chikuhō and Miike in the Fukuoka prefecture during the 1910s and 1920s, this article argues that the distribution of Koreans was a consequence of uneven capital accumulation among different mining companies. This unevenness reflected the differing wages and recruitment policies of these companies. Correlating earlier groups of cheap labourers, such as convict workers, to this history, we suggest some explanations as to why some mining companies brought Korean workers into the coal-production process as an immediately available, cheap, and disposable workforce, while others did not.