An electric parking brake adapted for use with a brake disk, the brake disk having a rotating axis, and opposite first and second side surfaces (210, 220) that are perpendicular to the rotating axis, said electric parking brake including: a main body unit including first and second side seats (11, 12) that are adapted to be located respectively at two sides of the brake disk, and that are adapted to be adjacent respectively to the first and second side surfaces (210, 220), said first side seat having a first recess that is adapted to be disposed in proximity to the first side surface, said second side seat having a second recess that is adapted to be disposed in proximity to the second side surface, said first and second recesses (111, 121) cooperating to form an accommodating space between said first and second side seats (11, 12); a lining unit including a first positioning member that is movable in said first recess along a central axis which is parallel to the rotating axis, a first lining that is secured on said first positioning member, a second positioning member that is movable in said second recess along the central axis, and a second lining that is secured on said second positioning member, said first and second linings (23, 24) being adapted to be adjacent respectively to the first and second side surfaces (210, 220); a braking unit including a first braking member that is movable in said first recess along the central axis, a second braking member that is movable in said second recess along the central axis, and a connecting member that has opposite side edges; and an actuating unit including a support that is fixedly connected to said connecting member, an actuator that is mounted on said support, and a driving shaft that extends along the central axis, and that is rotated by said actuator to move said first braking member relative to said main body unit, said driving shaft having a threaded portion that threadedly engages said first braking member such that, through operation of said actuator, said first lining is driven by said first braking member to move toward the first side surface in a direction to thereby move said second braking member toward the second side surface in an opposite direction, so that said first and second linings (22, 24) are moved toward each other to clamp the brake disk therebetween; characterized in that said main body unit further includes a pair of elongate guiding members spaced apart from each other, connected between said first and second side seats (11, 12), and extending parallel to the rotating axis and through said accommodating space, said connecting member of said braking unit further having a pair of hollow sliding portions that are disposed respectively on said side edges, and that are respectively and movably sleeved on said guiding members. a main body unit including first and second side seats (11, 12) that are adapted to be located respectively at two sides of the brake disk, and that are adapted to be adjacent respectively to the first and second side surfaces (210, 220), said first side seat having a first recess that is adapted to be disposed in proximity to the first side surface, said second side seat having a second recess that is adapted to be disposed in proximity to the second side surface, said first and second recesses (111, 121) cooperating to form an accommodating space between said first and second side seats (11, 12); a lining unit including a first positioning member that is movable in said first recess along a central axis which is parallel to the rotating axis, a first lining that is secured on said first positioning member, a second positioning member that is movable in said second recess along the central axis, and a second lining that is secured on said second positioning member, said first and second linings (23, 24) being adapted to be adjacent respectively to the first and second side surfaces (210, 220); a braking unit including a first braking member that is movable in said first recess along the central axis, a second braking member that is movable in said second recess along the central axis, and a connecting member that has opposite side edges; and an actuating unit including a support that is fixedly connected to said connecting member, an actuator that is mounted on said support, and a driving shaft that extends along the central axis, and that is rotated by said actuator to move said first braking member relative to said main body unit, said driving shaft having a threaded portion that threadedly engages said first braking member such that, through operation of said actuator, said first lining is driven by said first braking member to move toward the first side surface in a direction to thereby move said second braking member toward the second side surface in an opposite direction, so that said first and second linings (22, 24) are moved toward each other to clamp the brake disk therebetween; characterized in that said main body unit further includes a pair of elongate guiding members spaced apart from each other, connected between said first and second side seats (11, 12), and extending parallel to the rotating axis and through said accommodating space, said connecting member of said braking unit further having a pair of hollow sliding portions that are disposed respectively on said side edges, and that are respectively and movably sleeved on said guiding members.