  The SPICA coronagraph instrument (SCI) provides high-contrast imaging and
moderate resolution (R < 200) spectroscopy at the wavelength range from 3.5 to
27 \mu m. Based on the planet evolutional model calculated by Burrows et al.
(2003), SCI will search for gas giant planets down to one Jupiter mass around
nearby young (1 Gyr) stars and two Jupiter masses around nearby old (5 Gyr)
stars. SCI also allows to characterizing those planets of less than 1 Gyr by
spectroscopic observations to reveal the nature of planetary formation and
evolution. Focusing on the high sensitivity and high contrast at wavelengths
longer than 10 \mu m, we show that SCI also allows us to directly image icy
giant planets like Uranus and Neptune as well as gas giant planets around
nearby early-type stars. In this paper, we compare the capabilities of SCI and
the JWST coronagraphs and also discuss a new approach to answering questions
concerning the formation and evolution of planetary systems through planet
detection with SCI.
