Since solar system small bodies (SSSBs) are remnants from 
the early solar nebula, information on their composition and 
heterogeneity, and its relation to their dynamical history, 
helps us to understand the formation process and evolution
of planetesimals and planets in the solar nebula.

Infrared spectroscopy is a powerful tool to study the chemical 
composition of ice and the mineral composition of dust particles
for SSSBs. Most molecules in the SSSBs have strong fundamental 
bands of vibration in the near-infrared wavelength region. 
Silicate features are often observed for the dust from SSSBs as 
mid-infrared resonant features. 
AKARI, the Japanese infrared satellite, observed many SSSBs 
in the near- to far-infrared wavelength region. I will show 
the results of AKARI observations, in particular, 
the composition of cometary ice and interplanetary dust.