To provide a compound which has a laminin-5 production-promoting function, a basement membrane-caring function and an anti-ageing function and is useful as an anti-ageing agent, a basement membrane-caring agent and a laminin-5 production-promoting agent, and to provide the anti-ageing agent, the basement membrane-caring agent and the laminin-5 production-promoting agent which each has the laminin-5 production-promoting function, the basement membrane-caring function and the anti-ageing function and is useful as an external preparation for skin.

This new indole derivative and its salt. The anti-ageing agent, the basement membrane-caring agent and the laminin-5 production-promoting agent each comprises the new indole derivative or its salt, and the external preparation for skin contains the new indole derivative or its salt. The anti-ageing agent, the basement membrane-caring agent and the laminin-5 production-promoting agent each comprises a known indole derivative having the same structure and skeleton of the above-described new indole derivative or its salt, and the external preparation for skin contains the known indole derivative or its salt.