Abstract: A heat exchanger washing apparatus comprises a hopper for accommodating a plurality of washing brushes, a first heat exchanger leading guide having a first guide passage for guiding the washing brushes, a first opening/closing member for opening and closing the first guide passage, a first stopper disposed to the first guide passage, a second stopper, an air introduction passage communicating with the connecting port of the first guide passage downstream of the portion thereof where the first opening/closing member is disposed, a second opening/closing member for opening and closing the air introduction passage, a second heat exchanger leading guide connected to the first guide passage downstream of the connecting port and having a second guide passage for guiding the washing brushes with the extreme end of the second guide passage serving as an inserting portion which will be inserted into the pipe of a heat exchanger, first stopper control means, second stopper control means, first opening/closing control m