PROBLEM TO BE SOLVED : To provide a means whereby, after a pluripotent stem cell-derived cell or its structure is transplanted, it is possible to substantially prevent a tumor from occurring in the cell or its structure. SOLUTION : A composition contains a compound represented by formula (I). [L is C1-C6 alkylene carbonyl or the like; A is -NR3R4; R3 and R4 form, together with a nitrogen atom to which they bond, 4-7 membered heterocycloalkyl or heterocycloalkenyl containing one or more hetero atom selected from N, S and O]. SELECTED DRAWING : None COPYRIGHT : (C)2019, JPO&INPIT