The present invention has an object to provide a method for efficiently producing a human T cell population which has both cytotoxic and immunosuppressive activities, and solves the above object by providing a method for producing a human T cell population which has both cytotoxic and immunosuppressive activities, comprising the following steps (1) to (4):(1) fractionating mononuclear cells collected from a human umbilical cord blood into CD14-positive (CD14+) cells and CD14-negative (CD14−) cells, and then fractionating the CD14-negative (CD14−) cells into CD2-positive CD14-negative (CD2+CD14−) cells, and CD2-negative CD14-negative (CD2−CD14−) cells;(2) co-culturing the CD2-positive CD14-negative (CD2+CD14−) cells obtained in step (1) with stromal cells to generate blast cells;(3) adding the blast cells obtained in step (2) to the co-culture of the CD14-positive (CD14+) cells obtained in step (1) with stromal cells to allow the blast cells to proliferate; and(4) allowing the blast cells obtained in step (3) to further proliferate by co-culturing with stromal cells in the presence of interleukin-2 (IL-2) to generate a human T cell population which has both cytotoxic and immunosuppressive activities.