To solve a problem that some thermosetting resins contain hard materials so that a blade of a cutter is rapidly worn in a crusher using cutting and shearing, thereby deteriorating the durability of the crusher.

This crusher for synthetic resin is quipped with drive gear 4 and a driven gear 5, which are respectively attached to a drive shaft 2 and a driven shaft 3 parallel to each other and can rotate reversely to each other around the drive shaft 2 and the driven shaft 3, a drive means for rotating the drive gear 4, and a center distance varying means for varying the distance between the drive shaft 2 and the driven shaft 3, thereby crushing materials to be crushed, which are fed between the drive gear 4 and the driven gear 5 engaged with each other. When a crushed piece, having a thickness not allowed to pass through, of the material to be crushed is bitten between the gears, the center distance D between the drive gear 4 and the driven gear 5 is transiently increased.