The present invention relates to improvement to a bucket-type jaw crusher used for treatment of slag and other waste. In a bucket-type jaw crusher provided with a bucket (1) attached to an arm of a construction machine, a fixed jaw (5) fixed in the bucket, and a moving jaw (6) opposed to the fixed jaw (5) and pivotally supported on the top by an eccentric shaft (7) and supported on the bottom by a toggle mechanism and crushing slag and other materials to be crushed by reciprocating swing of the moving jaw (6), a motor (9) for rotating the eccentric shaft (7) forward and reverse is provided in the bucket and crushing control means is provided which automatically rotates the eccentric shaft (7) in reverse by the motor (9) and then, rotates the shaft forward when crushing the material to be crushed.