To provide a multiple disc brake device for a transmission capable of restraining a brake response delay by holding an oil quantity in a hydraulic pressure chamber.

A piston 10 performs brake operation by mutually bringing a rotary body side friction plate 21 and a friction plate 30 into pressure contact with each other by moving in the rotary shaft direction. An oil passage 6 supplying hydraulic pressure to the hydraulic pressure chamber 40 for pressing the piston 10 in the brake operation, and a lubricating oil passage 50 supplying the hydraulic pressure enough to maintain a brake in a non-operated state to the hydraulic pressure chamber 40, are connected to the hydraulic pressure chamber 40 partitioned and formed between a transmission case 2 and the piston 10. This lubricating oil passage 50 is connected to an upper end part of the hydraulic pressure chamber 40, and is formed as a small diameter part for limiting the hydraulic pressure leaking via the lubricating oil passage 50 in the brake operation.