To provide an incomplete-ice-melting structure of an ice-making machine which is so designed as to melt the incomplete ice in a feed water path surely and efficiently.

A supply water pipe 58 and a return pipe 48 communicating with an ice-making water tank 12 are made to branch from a case 24 of a pump 14. Inside the return pipe 48, a valve disk 62 which is pressed by a biasing means 64 and can close and open a flowing water port 56 is provided. This valve disk 62 is so displaced as to close up the flowing water port 56 under an ordinary pressure P1 acting during the operation of the pump 14, or below, and to open the flowing water port 56 on the occasion when a pressure P2 larger than the pressure P1 acts. In the case when the ordinary pressure P1 acts on the valve disk 62, in other words, ice making water is made to stay and held in the supply water pipe 58, and in the case when the pressure P2 acts on the valve disk 62 due to formation of incomplete ice, the ice-making water in the supply water pipe 58 is made to flow into feed water paths 20, 36 and 16 through the ice-making water tank 12 so as to melt the incomplete ice.