To provide a long or wide area marine structure capable of absorbing a displacement due to vibration at the time of thermal expansion/contraction and an earthquake even when a plurality of jackets are connected by unilateral telescopic joints.

The marine structure is provided with a submarine foundation, a lower frame structure connected to the submarine foundation, a superstructure connected to the lower frame structure, and a floor slab put on the superstructure. The superstructure is arranged astride the lower frame structures. Accordingly, a highly rigid structure can be formed. Further, since the relative displacements of mutual side edges positioned opposite to the floor slab are made small, it is possible to connect the mutual floor slabs by unilateral telescopic joints.