With respect to a clean air device, in order to provide a device structure and an air cleaning unit inspecting method capable of supplying clean air through a filter and also capable of measuring the amount of dust in a workroom space in which blown air forms a laminar flow such that an increase in the amount of dust can be accurately detected, the clean air device comprises an air cleaning unit, a rectifying unit arranged downstream of the air cleaning unit configured to rectify air blown from the air cleaning unit and form a laminar flow, and a workroom arranged downstream of the rectifying unit, wherein at least one suction port is provided on a wall surface in a space formed between the air cleaning unit and the rectifying unit, configured to draw out the air in the space to an exterior.