An object of the present invention is to provide a two-photon-absorbing compound which is excellent in water-solubility, is excited by two-photon absorption in a near-infrared wavelength region, and emits a red fluorescence. A compound represented by formula (1) [wherein X 1 and X 2 are the same or different, and each represents the following formula (2) (wherein R 1 represents a C1-C3 alkyl group, Z - represents a counter anion to a pyridinium cation, and a wavy line represents a covalent bond to Y), and Y represents a condensed polycyclic group having 2 to 4 rings] is excellent in water-solubility, is excited by two-photon absorption in a near-infrared wavelength region, and emits a red fluorescence. €ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒX 1 -Y-X 2 €ƒ€ƒ€ƒ€ƒ€ƒ(1)
