The present invention relates to a target-activated cell/tissue-penetrating peptide for delivery of impermeable compounds (Target Activated Cell/tissue Translocation peptide for Impermeable Compound Strategy (TACTICS)) , and the use thereof, and more particularly to a target-activated cell/tissue-penetrating peptide, which comprises (a) a protein transduction domain (PTD), (b) a masking domain and (c) a spacer having a cleavage site specific for a target cell/tissue enzyme and is provided with target selectivity so as to penetrate specifically into a target tissue, and to a conjugate of the peptide with a drug or drug-containing particles for imaging or therapeutic applications. Because the target-activated cell/tissue-penetrating peptide has target selectivity, the peptide-drug conjugate exhibits maximized imaging and therapeutic effects, and the non-specific distribution of the conjugate in vivo is inhibited, so that the side effects of the conjugate are minimized, the diagnostic effects of the conjugate are maximized, and the conjugate is useful for the treatment of disease.
