A hearing aid device with a dichotic function comprises a first sound input/output component having a first microphone configured to be worn on one ear, a second sound input/output component having a second microphone configured to be worn on the other ear, and a dichotic setting component. The dichotic setting component determines the occurrence of time masking according to a sound signal inputted from the first microphone or the second microphone, and activates or deactivates the dichotic function according to this determination result. The hearing aid device improves the hearing aid effect.