Abstract
We investigate effects of change in dust size due to evaporation on the dust orbit and surface density. Some dust-debris disks have inner holes. The dust migrate inward due to Poynting-Robertson drag and the migration time is shorter than the age of central stars. The dust-debris disks would have dust sources. Even if the dust production region also have inner hole, the inner hole disappears because the surface density is constant for radial location due to dust migration due to Poynting-Robertson drag. If the dust size become smaller due to evaporation, samimajor axis and eccentricity of dust increase. Then, residual dust migrate inward faster. If the size distribution of dust is desided by collision cascade, the surface density for dust with size $d$ decrease at the snow line storongly. Thus, the brightness density would change at the snow line strongly, too.
