PURPOSE: To provide a multi-disc brake device whose number of items is reduced so as to facilitate assembling.

CONSTITUTION: A plurality of friction plates 48 are fitted to a motion receiving base 46 whih is fixed to a rotary shaft 14 journalled to a case 10 movably in an axial direction and a plurality of steel plates 50 and friction plates 48 are alternately arranged on the case 10, and fitted movably in an axial direction while friction plates 48 and the the steel plates 50 are pressed against each other so as to apply braking force to the rotary shaft 14. In such a multi-disc brake device 22, a large diameter portion is formed on a leading end of the motion receiving base 46 in an assembling direction for regulating escape of the friction plates 48.