  Water masers around an AGB star, IRC+60169, were observed at four epochs
using the Japanese VLBI networks. The distribution of the maser features is
limited in a thick-shell region, which has inner and outer expansion velocities
of 7 km/s and 14 km/s at radii of 25 mas and 120 mas, respectively. The
distribution of the red-shifted features exhibits a ring-like structure, the
diameter of which is 30 mas, and corresponds to the inner radius of the maser
shell. This implies that dense gas around the star obscures red-shifted
emission. Although a position--radial velocity diagram for the maser features
is consistent with a spherical shell model, the relative proper motions do not
indicate an expansion motion of the shell. A remarkable property has been found
that is a possible periodic change of the alignment pattern of water maser
spots.
