This hearing aid comprises a microphone (1) for collecting sounds, an A/D converter (2) for converting an analog signal outputted from the microphone (1) into a digital signal, a hearing aid processor (3) for performing hearing aid processing on the digital signal outputted from the A/D converter (2), a D/A converter (4) for converting the signal that has undergone the hearing aid processing into an analog signal, and a receiver (5) for outputting the analog signal outputted from the D/A converter (4) as an acoustic signal to the surroundings. A mixer (6), in which a first input is connected to the output of the hearing aid processor (3) and its own output is connected to the input of the D/A converter (4), is interposed between the hearing aid processor (3) and the D/A converter (4). The output signal of an alert sound shaper (8) that shapes the alert sound signal produced by an alert sound producer (7) is connected to a second input of the mixer (6). The mixer (6) is connected to a controller (9) that produces a mix ratio signal for mixing the output signals of the hearing aid processor (3) and the alert sound shaper (8).