A parts-mass compressing device includes a base stand having a table structure on which a mass of vertically standing raised workpieces are disposed. A stopper plate is fixed to one end of said table structure and a moving plate is movable toward and away from said stopper plate. Movement of the moving plate toward said stopper plate compresses the mass. A toggle mechanism drives the moving plate and has first and second toggle links which are pivotally connected at their inner ends. The inner ends are connected to a power cylinder.