An object of the present invention is to provide novel apoptosis inhibitors and therapeutic agents for inner ear hearing impairment. As a pharmaceutical agent for this purpose, a rapamycin derivative represented by the following structural formula (II) as an active ingredient is provided:wherein R1 is a C1-6 alkyl or a C3-6 alkynyl, R2 is H, -CH2-OH or -CH2-CH2-OH, and X is =O, (H, H) or (H, OH).