A novel heterodimeric antibody for treating B cell lymphoma or leukemia.Solution: an anti-cd123 Fab FC heavy chain sequence 1 having specific sequences, an anti cd3scfv FC heavy chain array 2 having a particular sequence, and a heterodimeric antibody comprising an anti CD123 light chain array having a specific sequence.No selection【課題】B細胞リンパ腫又は白血病を治療するための新規なヘテロ二量体抗体の提供。【解決手段】特定の配列を有する抗CD123Fab-Fc重鎖配列1、特定の配列を有する抗CD3scFv-Fc重鎖配列2、及び特定の配列を有する抗CD123軽鎖配列を含むヘテロ二量体抗体の提供。【選択図】なし