A brake apparatus comprising: an operation member; a brake cylinder (14a-14d; 116a; 117a; 121b-124b); an electric braking-force control device (13; 120; 141) for electrically controlling a braking force in accordance with an operation amount or force of said operation member; a master cylinder for producing pressure of a brake fluid; and a transmission unit for operatively connecting said operation member to said master cylinder, said transmission unit being capable of varying a ratio between an output amount of an output member thereof connected to said master cylinder and the operation amount of said operation member; a block member (18, 19, 55a, 55b) for blocking communication of the brake fluid between said master cylinder and said brake cylinder (14a-14d; 116a; 117a; 121b-124b); and a simulator for accumulating the brake fluid supplied from the master cylinder, wherein, in a normal operation, with the communication of the brake fluid between said master cylinder and said brake cylinder (14a-14d; 116a; 117a; 121b-124b) blocked by said block member (18, 19, 55a, 55b), the braking force of said brake cylinder (14a-14d; 116a; 117a; 121b-124b) is controlled, via said electric braking-force control device (13; 120; 141), in accordance with the operation amount or force of said operation member in a former-half operation amount region of the operation amount of said operation member, in which the amount of the brake fluid supplied from the master cylinder to the simulator is controlled via said transmission unit not to become greater than an accumulation amount of the brake fluid in said simulator, and wherein, in an abnormal operation of said electric braking-force control device (13; 120; 141), with said block member (18, 19, 55a, 55b) placed in an opened state, the fluid pressure of said master cylinder is supplied directly to said brake cylinder (14a-14d; 116a; 117a; 121b-124b), wherein, in a latter-half operation amount region (E2; E6; E9) of the operation amount of said operation member, which corresponds to a region in which the amount of the braking fluid supplied from said master cylinder exceeds the accumulation amount of the braking fluid in said simulator, a ratio of the operation amount of said operation member to the output amount of the output member is controlled, via said transmission unit, to increase in response to increase of the operation amount of said operation member. an operation member; a brake cylinder (14a-14d; 116a; 117a; 121b-124b); an electric braking-force control device (13; 120; 141) for electrically controlling a braking force in accordance with an operation amount or force of said operation member; a master cylinder for producing pressure of a brake fluid; and a transmission unit for operatively connecting said operation member to said master cylinder, said transmission unit being capable of varying a ratio between an output amount of an output member thereof connected to said master cylinder and the operation amount of said operation member; a block member (18, 19, 55a, 55b) for blocking communication of the brake fluid between said master cylinder and said brake cylinder (14a-14d; 116a; 117a; 121b-124b); and a simulator for accumulating the brake fluid supplied from the master cylinder, wherein, in a normal operation, with the communication of the brake fluid between said master cylinder and said brake cylinder (14a-14d; 116a; 117a; 121b-124b) blocked by said block member (18, 19, 55a, 55b), the braking force of said brake cylinder (14a-14d; 116a; 117a; 121b-124b) is controlled, via said electric braking-force control device (13; 120; 141), in accordance with the operation amount or force of said operation member in a former-half operation amount region of the operation amount of said operation member, in which the amount of the brake fluid supplied from the master cylinder to the simulator is controlled via said transmission unit not to become greater than an accumulation amount of the brake fluid in said simulator, and wherein, in an abnormal operation of said electric braking-force control device (13; 120; 141), with said block member (18, 19, 55a, 55b) placed in an opened state, the fluid pressure of said master cylinder is supplied directly to said brake cylinder (14a-14d; 116a; 117a; 121b-124b), wherein, in a latter-half operation amount region (E2; E6; E9) of the operation amount of said operation member, which corresponds to a region in which the amount of the braking fluid supplied from said master cylinder exceeds the accumulation amount of the braking fluid in said simulator, a ratio of the operation amount of said operation member to the output amount of the output member is controlled, via said transmission unit, to increase in response to increase of the operation amount of said operation member.