We present a magnetic field mapping of water maser clouds in the star-forming region W3 IRS 5 , which has been made on the basis of the linear polarization VLBI observation .
Using the Very Long Baseline Array ( VLBA ) at 22.2 GHz , 16 of 61 detected water masers were found to be linearly polarized with polarization degrees up to 13 % .
Although 10 polarized features were widely distributed in the whole W3 IRS 5 water maser region , they had similar position angles of the magnetic field vectors ( \sim 75 ^ { \circ } from the north ) .
The magnetic field vectors are roughly perpendicular to the spatial alignments of the maser features .
They are consistent with the hourglass model of the magnetic field , which was previously proposed to explain the magnetic field in the whole W3 Main region ( r \sim 0.1 pc ) .
They are , on the other hand , not aligned to the directions of maser feature proper motions observed previously .
This implies that the W3 IRS 5 magnetic field was controlled by a collapse of the W3 Main molecular cloud rather than the outflow originated from W3 IRS 5 .