PROBLEM TO BE SOLVED : To provide a conjugate including a pyrrolobenzodiazepine dimer compound having a linker connected to a cell binding agent. SOLUTION : The present invention provides a conjugate compound of formula (A) (where groups of R each have a specific substituent, Y is a substituent including a cell binding agent, Z is CH or N; T and T' are independently selected from a single bond or C1-9 alkylene; X and X' are independently selected from O, S and N(H)). SELECTED DRAWING : None COPYRIGHT : (C)2019, JPO&INPIT