To provide a cooker like a food processor to work vegetables with the improved safety by allowing an engaging lug part of a rotary drive shaft to engage an engaging recess part of a disk and a fastening member to threadingly engage the rotary drive shaft so that the disk does not get out of the rotary drive shaft during use.

When a disk 55 is a braying cutter for example which is secured fixedly to a rotary drive shaft, first the rotary drive shaft 60 is inserted into an engaging hole 55a of the disk 55 from above the disk. A screw lug part 64 of the rotary drive shaft 60 is inserted into a through hole 58 of the disk 55 to make engaging lug parts 62, 62 contact with engaging recess parts 57, 57 of the disk 55 respectively. Next, a fastening member 71 is inserted in the rotary drive shaft 60 from the lower end and moved upward. After the screw lug part 64 abuts against a screw lug part 71a of the fastening member 71, the fastening member 7 is rotated so that the screw lug part 71a threadingly engages the screw lug part 64 to fixedly engage and fasten the rotary drive shaft 60.