A lubricating oil supply device of a power transmission device (1-1 to 1-5) comprising: a storage portion configured to store lubricating oil; a first rotary member configured to be connected to a wheel of a vehicle and rotated in conjunction with a rotation of the wheel to send the lubricating oil of the storage portion; a second rotary member configured to be disposed above the first rotary member in a vertical direction and connected to the wheel; an oil receiving portion configured to be disposed above the first rotary member and the second rotary member in the vertical direction; a first passage configured to guide the lubricating oil, which is sent by the rotation of the first rotary member, to the oil receiving portion; a second passage configured to guide the lubricating oil, which is sent by the rotation of the first rotary member, to the second rotary member; an outer peripheral flow passage configured to extend along an outer periphery of the first rotary member and guide the lubricating oil, which is sent by the rotation of the first rotary member, to the upper side in the vertical direction; wherein the first passage and the second passage are connected to the outer peripheral flow passage, respectively, a second inlet that is an inlet to the second passage from the outer peripheral flow passage is positioned on the outer peripheral flow passage on the downstream side of a first inlet that is an inlet to the first passage from the outer peripheral flow passage, in a flow direction of lubricating oil, and the second rotary member is rotated in conjunction with the rotation of the wheel to send the lubricating oil which is sent through the second passage to the upper side in the vertical direction, characterized in that the cross-sectional area (G3-Fig.6) of the outer peripheral flow passage on the downstream side of the second inlet in the flow direction is smaller than the cross-sectional area (G1-Fig.6) of the outer peripheral flow passage on the upstream side of the second inlet in the flow direction. a storage portion configured to store lubricating oil; a first rotary member configured to be connected to a wheel of a vehicle and rotated in conjunction with a rotation of the wheel to send the lubricating oil of the storage portion; a second rotary member configured to be disposed above the first rotary member in a vertical direction and connected to the wheel; an oil receiving portion configured to be disposed above the first rotary member and the second rotary member in the vertical direction; a first passage configured to guide the lubricating oil, which is sent by the rotation of the first rotary member, to the oil receiving portion; a second passage configured to guide the lubricating oil, which is sent by the rotation of the first rotary member, to the second rotary member; an outer peripheral flow passage configured to extend along an outer periphery of the first rotary member and guide the lubricating oil, which is sent by the rotation of the first rotary member, to the upper side in the vertical direction; wherein the first passage and the second passage are connected to the outer peripheral flow passage, respectively, a second inlet that is an inlet to the second passage from the outer peripheral flow passage is positioned on the outer peripheral flow passage on the downstream side of a first inlet that is an inlet to the first passage from the outer peripheral flow passage, in a flow direction of lubricating oil, and the second rotary member is rotated in conjunction with the rotation of the wheel to send the lubricating oil which is sent through the second passage to the upper side in the vertical direction, characterized in that the cross-sectional area (G3-Fig.6) of the outer peripheral flow passage on the downstream side of the second inlet in the flow direction is smaller than the cross-sectional area (G1-Fig.6) of the outer peripheral flow passage on the upstream side of the second inlet in the flow direction.