A method is provided by which a reagent is provided to a living sample, including contacting a thin-film containing a porous body with a living sample containing cells or tissues, and discharging a solution containing at least one or more reagents to a non-contact side of the thin-film by ink-jet to provide the solution to the specific area of the living sample through pores on the thin-film, wherein the smaller diameter of the pores on the porous body relative to the diameter of cells in the living sample enables the reagent to be provided to each individual cell separately. According to this method, the reagent and the reaction product can be fixed while maintaining positioning information of the target substance in the living sample, as a pretreatment for analyzing with high positioning accuracy the target substance in each individual cell in the living sample.