The present invention relates to a pharmaceutical composition for preventing or treating a heart failure and a method for screening a therapeutic agent for preventing or treating a heart failure. The pharmaceutical composition of the present disclosure comprises the CCN5 or CCN2ΔCT protein, or a genetic carrier comprising a nucleotide sequence encoding the CCN5 or the CCN2ΔCT protein, exhibiting dramatic prevention or treatment efficacies on a heart failure even without surgical treatments accompanied with transplanting a donor heart.
