An in-vehicle component attachment structure 8 includes a front body inner section 5 and a reinforcement panel 6. The front body inner section 5 includes a second wall 17 fixed on the vehicle side, and an attaching part 18 integratedly formed by bending the second wall 17. The reinforcement panel 6 is arranged near the attaching portion 18 and fixed on a side of the second wall 17 in the vicinity of the attaching portion 18, and fixed making surface contact with this side. The attaching portion 18 includes an attaching surface 22 to which a wiper motor unit is fastened and fixed. The attaching surface 22 is at a slant relative to the second wall 17 at a predetermined angle in accordance with the fastening direction of the wiper motor unit.