Problem to be solved. To provide a method for activating skin stem cells, a skin stem cell activation agent, and a screening method for skin stem cell activation agents. Solution. The application of an MPC1 suppressant is effective in activating skin stem cells. Examples of such MPC1 suppressants include agents that include at least an akebia extract, a black bean extract, a peony extract, a tea extract, a jojoba leaf extract, or ergothioneine as an active ingredient. Moreover, skin stem cell activation agents can be screened using MPC1 suppression action as an index.