Conjugate of phthalocy anine dye and antibody or peptide

A compound represented by the following formula (1) or a salt thereof:

• wherein
• X represents a substituent having a sulfonic group at the terminus thereof,
• L3 repesents
• wherein m represents an integer of 1 to 5,
• L4 represents —[(CH2)p—O)]q— wherein p and q each independently represent an integer of 1 to 5), or —(CH2)r— wherein r represents an integer of 1 to 5,
• L5 represents —CONH—, —NHCO—, —COO—, —OCO—, —CO-(Xaa)s-NH—, or —NH-(Xaa)r-CO— wherein s and t represent an integer of 1 to 10, and Xaa represents an amino acid residue having a hydrophilic group at the terminus of a side chain thereof,
• L6 represents —(CH2)r—Si(R1)(R2)—O— wherein r represents an integer of 1 to 5, and R1 and R2 each independently represent an alkyl group containing 1 to 4 carbon atoms,
• Y represents an active ester of a carboxyl group,
• R3 represents an alkoxy group containing 1 to 6 carbon atoms, a halogen atom, —SR11, —SOR12, —N(R13)(R14), or —NO2,
• R11, R12, R13, and R14 each independently represent an alkyl group containing 1 to 6 carbon atoms or an alkoxy group containing 1 to 6 carbon atoms,
• wherein the alkyl group represented by R3, R11, R12, R13 and R14, and the alkoxy group represented by R11, R12, R13 and R14 may be optionally substituted with a halogen atom, and
• when a plurality of R3s are present, the plurality of R3s may be identical to or different from one another, and
• s represents an integer of 0 to 2.