In order to provide a wiper-cooperative washing apparatus which adjusts the jetting rate and jetting timing of a washing liquid, thereby preventing waste of the washing liquid, an attachment nozzle pipe 7 for washing a glass surface W of a vehicle is removably attached to a wiper blade 1c, the attachment nozzle pipe 7 has nozzle openings 7d2, 7e2 and 7j from which the washing liquid is jetted toward the forward-wiping side of a blade rubber 1d, when a washer switch 6 is turned on, an arm 1a supporting the wiper blade 1c is swung forward and backward a predetermined number of times, during every forward swing of the arm 1a, a washer pump 2 is kept operating until 55% to 75% of one forward wiping stroke is completed, thereby adjusting the jetting rate of the washing liquid.