This paper explores the sources of Japanese CEO power and the processes through which power is acquired. Japanese CEOs realise two types of power, positional and personal. Positional power derives from strategic contingencies which encompass the office CEO. It also arises from institutional dimensions of the office's role within an organisation and within society. Personal power has two basic components and is a consequence of Japanese human resource management processes which are predicated upon an internal labor market. Slow promotion and job rotation provide managers with the opportunity to acquire expert influence and to build extensive acquaintance networks. Promotions legitimise the acquisition of power. CEO power is moderated by factors which directly influence the extent of legitimacy which is accorded both the individual and the office.