Abstract
We examine planetesimal formation through direct dust growth. Our group showed that icy dust aggregates stick to each other at their collision for an impact velocity less than several tens m/sec. Thus it is worthwhile to examine planetesimal formation through direct dust growth. We compare the growth time of dust with the time scale of dust falling to the sun. As a result, we found that dust aggregates can grow before their falling if they settle to the mid-plane of gaseous disks. When dust aggregates grow to km-size, their self-gravity is effective and the mode of their growth would change to runaway.