Abstract: The present invention relates to a bispecific antibody that binds to human CD19 and CD3, wherein the bispecific antibody is composed of a Fab fragment which specifically recognizes a cell membrane antigen and a single-chain antibody which recognizes a CD3 molecule, where the single-chain antibody which recognizes the CD3 molecule is linked to the C-terminus of the CH1-region peptide fragment of the Fab fragment through a hydrophilic linker peptide-linker; and where the Fab fragment which specifically recognizes a cell membrane antigen contains a Fab structure which specifically recognizes a human CD19 antigen, and the bispecific antibody has the following structure: where the linker peptide-linker is composed of 8-20 hydrophilic amino acids.