A pressure generating apparatus includes a master cylinder and a stroke simulator which has a pressure chamber communicated with a first master chamber, an atmospheric chamber communicated with a reservoir, and a piston member urged by a resilient member, and which absorbs brake fluid in response to the hydraulic pressure discharged from the first master chamber, to provide a stroke for a first master piston. The atmospheric chamber of the simulator is communicated with the reservoir when a second master piston member is placed in an initial position thereof, and blocks the communication between them, when the second master piston is advanced by a predetermined distance or more from the initial position.