To omit the fixing work of a spindle guide performed by fastening a nut by supporting a spindle connected to an operation handle or the like so as to penetrate an attaching member and be freely rotated and integrally forming a guide part communicated with the through-hole of the spindle in the attaching member.

A guide part 11 communicated with a spindle through-hole 10 is integrally formed in the outer surface of a low tank wall (t) as an attaching member. A spindle 20 is passed through the through-hole 10 of the low tank wall (t), the projection 23 of its tip is inserted and pushed into the through-hole 12a of an operation handle 12, the selation part 22 of the spindle 20 and the selation part 12b of the operation handle 12 are engaged with each other and both are connected to each other and supported so as to be freely rotated. Thus, the work of fixing the spindle guide 11 by fastening a nut is omitted and assembling work is simplified.