Treatment with an acoustic catheter is disclosed. A photoacoustic catheter system includes an imaging laser beam generator that generates an imaging laser beam used for imaging; a treatment laser beam generator that generates a treatment laser beam used for treatment; a driver that provides driving to cause the imaging laser beam and the treatment laser beam to be emitted in a predetermined direction with respect to an advancing direction of a catheter; an acoustic element that receives an acoustic wave generated due to irradiation of the imaging laser beam; and a treatment laser beam controller, wherein the treatment laser beam controller synchronously emits the imaging laser beam and the treatment laser beam so as to be directionally aligned with each other.