The effect of air flow on a weighing dish is minimized by the following relatively simple arrangement. A mounting member (1) having a protection dike (1D), an engaging ridge (1B), and a outermost peripheral engaging wall (1A) formed in a concentric manner about an opening (1C) to insert therethrough a connecting portion (2A) is disposed on an upper casing (3) of a weighing device located on a lower surface of a weighing dish (2). First and second windproof walls (4, 5) are positioned by fitting to an inner peripheral wall of the engaging ridge 1B and the engaging wall (1A), respectively, and can be easily removed when necessary, such as for cleaning. For example, the second windproof wall (5) is formed higher than the first windproof wall (4), thereby enabling effective obstruction of air flow from the outside.