To provide a particle promoting hydrophobic metal phthalocyanine aggregation, having absorption in a wavelength region suitable for a photoacoustic imaging method and having a high molar absorbance coefficient per particle by increasing the weight percentage of the dye in the particle. The particle of the present invention is a particle having a hydrophobic metal phthalocyanine and a surfactant, wherein the weight percentage of the hydrophobic metal phthalocyanine is 6% or more.