To prevent a whole apparatus from being destroyed by making a turning part turning by a direct current electric motor be directly turned without providing a clutch mechanism.

At the turning part A provided to the rear part of a crusher body 1 of a small crusher for construction, the turning part A is driven by the direct current electric motor M via a speed reduction gear mechanism. The crusher body 1 is directly joined to the direct current electric motor M via no brake mechanism and no clutch mechanism. Operation of the crusher is controlled so that a value of (moment of inertia IM of the direct current electric motor M)×(speed reduction ratio)2 becomes smaller than the value of moment of inertia ID of the crusher.