Provided is an auditory sensitivity adjustment device suitable to enhance concentration and attentiveness in any direction. An auditory sensitivity adjustment device 100 includes grab parts 32a and 32b for holding a pinna 50, springs 22 for applying to the grab parts 32a and 32b a force for pulling, in an extending direction, the pinna 50 held by the grab parts 32a and 32b, and a base 38 for rotating the pinna 50 held by the grab parts 32a and 32b so as to twist the pinna 50.