To provide a connecting structure of an embedded foundation block, an embedded foundation block and a connecting plate which prevent scouring and have excellent workability as well as water stopping property.

In a connecting structure to connect embedded foundation blocks 10 each other which are embedded lower than a planned river bed A, the embedded foundation block 10 has a plate-like body section 20 vertically extended with respect to a horizontal surface. Either of right and left end surfaces of the body section is provided with a female fitting section 60 and the other end surface is provided with a male fitting section 50. By fitting the female fitting section of one of the two neighboring embedded foundation blocks with the male fitting section of the other embedded foundation block, the two embedded foundation blocks are connected in a manner that allows the same to relatively rotate in a horizontal direction.