An anchor device for anchoring a floating structure to the seabed with an anchor chain having a shackle at one end of the chain. The anchor device includes a mooring bolt for being inserted into a borehole drilled in the seabed and a support plate having a lower face for resting on the seabed and an upper face with a through hole through which the mooring bolt passes through the support plate for being inserted into the borehole. The upper face of the support plate has a connection point for coupling the shackle of the end of the chain, such that when the floating structure is anchored to the seabed, the chain is subjected to tensile stresses causing a force to be applied at the connection point and not directly to the mooring bolt.