A transmission lubricating assembly for a helicopter, the transmission lubricating assembly comprising: a transmission including a speed change structure that is configured to be able to change the speed of rotation produced by rotational power input from a prime mover and output the resulting rotational power and a housing accommodating the speed change structure ; and a lubricator that lubricates the speed change structure , wherein the lubricator includes a collector that collects a mist of a lubricating oil in an internal space (S) of the housing and a dropper that is disposed below the collector and that applies droplets of the lubricating oil to the speed change structure , the droplets resulting from the collected mist being gathered under its own weight, characterised in that the lubricator further includes a shaft structure extending in a horizontal direction and a tubular structure disposed to enclose an outer peripheral surface of the shaft structure , with a gap (G) defined between an inner peripheral surface of the tubular structure and the outer peripheral surface of the shaft structure , one axial end of the tubular structure is located below the other axial end of the tubular structure , the collector includes the outer peripheral surface of the shaft structure , an end surface of the shaft structure , and the inner peripheral surface of the tubular structure , the end surface of the shaft structure being located towards the one axial end of the tubular structure , the droplets of the lubricating oil are retained in the gap (G), and the dropper includes a lowermost point of a region of the shaft structure and a lowermost point of a region of the tubular structure , the regions facing each other across the gap (G). a transmission including a speed change structure that is configured to be able to change the speed of rotation produced by rotational power input from a prime mover and output the resulting rotational power and a housing accommodating the speed change structure ; and a lubricator that lubricates the speed change structure , wherein the lubricator includes a collector that collects a mist of a lubricating oil in an internal space (S) of the housing and a dropper that is disposed below the collector and that applies droplets of the lubricating oil to the speed change structure , the droplets resulting from the collected mist being gathered under its own weight, characterised in that the lubricator further includes a shaft structure extending in a horizontal direction and a tubular structure disposed to enclose an outer peripheral surface of the shaft structure , with a gap (G) defined between an inner peripheral surface of the tubular structure and the outer peripheral surface of the shaft structure , one axial end of the tubular structure is located below the other axial end of the tubular structure , the collector includes the outer peripheral surface of the shaft structure , an end surface of the shaft structure , and the inner peripheral surface of the tubular structure , the end surface of the shaft structure being located towards the one axial end of the tubular structure , the droplets of the lubricating oil are retained in the gap (G), and the dropper includes a lowermost point of a region of the shaft structure and a lowermost point of a region of the tubular structure , the regions facing each other across the gap (G). <EOS>