A vehicle drive device comprising: an input member drivingly connected to an internal combustion engine; a rotary electric machine including a stator (St) and a rotor (Ro) that is disposed on an inner side in a radial direction with respect to the stator (St), and functioning as a driving force source for wheels; a transmission that changes a speed of rotation transmitted from the rotary electric machine side; a rotor support member that supports the rotor (Ro); a rotation sensor that detects rotation of the rotor (Ro); and a first engagement device disposed on the inner side in the radial direction with respect to the rotor (Ro), the first engagement device being disposed in a power transmission path between the rotary electric machine and the transmission, wherein: the first engagement device includes a first friction member and a first piston portion that presses the first friction member in an axial direction; when in the axial direction, one side in the axial direction with respect to the first engagement device is defined as a first side in the axial direction, and a side opposite to the first side in the axial direction is defined as a second side in the axial direction, the rotor support member includes a tubular portion having a tubular shape extending along the axial direction and supporting the rotor (Ro), and a flange portion provided to extend along the radial direction on the inner side in the radial direction with respect to the tubular portion at a position adjacent to the first engagement device on the first side in the axial direction, and connected to the tubular portion; the flange portion includes a cylinder forming portion protruding to the first side in the axial direction so as to form a cylinder portion on which the first piston portion slides; characterized in that the rotation sensor includes a rotating body supported by an outer peripheral surface of the cylinder forming portion on an outer side in the radial direction, and a fixed body disposed on the outer side in the radial direction with respect to the rotating body. an input member drivingly connected to an internal combustion engine; a rotary electric machine including a stator (St) and a rotor (Ro) that is disposed on an inner side in a radial direction with respect to the stator (St), and functioning as a driving force source for wheels; a transmission that changes a speed of rotation transmitted from the rotary electric machine side; a rotor support member that supports the rotor (Ro); a rotation sensor that detects rotation of the rotor (Ro); and a first engagement device disposed on the inner side in the radial direction with respect to the rotor (Ro), the first engagement device being disposed in a power transmission path between the rotary electric machine and the transmission, wherein: the first engagement device includes a first friction member and a first piston portion that presses the first friction member in an axial direction; when in the axial direction, one side in the axial direction with respect to the first engagement device is defined as a first side in the axial direction, and a side opposite to the first side in the axial direction is defined as a second side in the axial direction, the rotor support member includes a tubular portion having a tubular shape extending along the axial direction and supporting the rotor (Ro), and a flange portion provided to extend along the radial direction on the inner side in the radial direction with respect to the tubular portion at a position adjacent to the first engagement device on the first side in the axial direction, and connected to the tubular portion; the flange portion includes a cylinder forming portion protruding to the first side in the axial direction so as to form a cylinder portion on which the first piston portion slides; characterized in that the rotation sensor includes a rotating body supported by an outer peripheral surface of the cylinder forming portion on an outer side in the radial direction, and a fixed body disposed on the outer side in the radial direction with respect to the rotating body. the first engagement device includes a first friction member and a first piston portion that presses the first friction member in an axial direction; when in the axial direction, one side in the axial direction with respect to the first engagement device is defined as a first side in the axial direction, and a side opposite to the first side in the axial direction is defined as a second side in the axial direction, the rotor support member includes a tubular portion having a tubular shape extending along the axial direction and supporting the rotor (Ro), and a flange portion provided to extend along the radial direction on the inner side in the radial direction with respect to the tubular portion at a position adjacent to the first engagement device on the first side in the axial direction, and connected to the tubular portion; the flange portion includes a cylinder forming portion protruding to the first side in the axial direction so as to form a cylinder portion on which the first piston portion slides; characterized in that the rotation sensor includes a rotating body supported by an outer peripheral surface of the cylinder forming portion on an outer side in the radial direction, and a fixed body disposed on the outer side in the radial direction with respect to the rotating body.