AKARI 2.5–4.5 μm spectra taken from the 34 regions in M 82, the positions of which are shown in Fig. 1. The blue linear baselines are determined at the wavelength ranges of 3.0–3.2 μm and 3.7–3.9 μm. For the spectra with significant detection of the excess emission, the red curves indicate the best-fit Drude profiles representing the contribution of the aromatic 3.3 μm emission, which are determined at the wavelength range of 3.20–3.35 μm.