To fix vertically annexed wall panels more firmly without twisting in a bathroom unit, in which an opening section for installing a door frame or a window frame having specified size is formed to one wall surface and the vertically annexed wall panels and horizontally annexed wall panels are arranged on the outsides along at least vertical and horizontal each one side of the opening section respectively.

In the bathroom unit, the mutually adjacent one side end sections of vertically annexed wall panels 14 and horizontally annexed wall panels 12 are both mounted at connecting angles 18 set up at the corners of a bathroom and used for connecting the wall panels. Joiners 58 are retained detachably at the other side end sections separated from connecting places with the connecting angles 18 in the vertically annexed wall panels 14 at that time, and the joiners 58 are coupled and fixed to the horizontally annexed wall panels 12.