The present invention provides a method for efficiently producing highly pure γδT cells introduced with foreign genes by culturing in the presence of IL-7 and IL-15 after stimulating the γδT cells with a bisphosphonic acid ester derivative. When a
T cell receptor (TCR) or a
chimeric antigen receptor (CAR) is introduced as a foreign
gene, γδT cells in which TCR and CAR are functionally expressed can be obtained.