Kinetics of J-aggregation of thiacarbocyanine (THIATS) has been investigated by measuring time variation of fluorescence spectrum under the solvent evaporation process of THIATS solution. Fluorescence spectrum of the THIATS J-aggregates changes following the increase of concentration, reflecting the formation and ripening process of J-aggregates. These THIATS J-aggregates are trapped and gathered at the focal point by focusing near-infrared (NIR) laser beam into the solution. Two-photon excited fluorescence from the focal spot is concurrently detected with the same trapping laser beam. Fluorescence spectral change is accelerated by focusing NIR laser beam. This result could be attributed that J-aggregates with higher polarizability are preferably formed in the focal spot of NIR laser. Furthermore, we have succeeded in the deposition of J-aggregates on a glass substrate by optical trapping.