Using an original data set, we investigated the determinants of individual preferences over income redistribution in Japan. Although income level is negatively correlated with support for redistribution, it does not explain much; there are other important factors that relate to dynamics and uncertainty, such as income risk. Even after controlling for income, both risk-averse individuals and those who expect to be unemployed in the future favour greater redistribution. Interaction of ageing and mobility prove important. The relatively poor elderly, who presumably have few prospects of upward mobility, strongly support greater redistribution, whereas younger people are less sympathetic to such a policy.