There are certain preliminary essential condition which must be complied with in order to render the insurer liable under a contract of marine cargo insurance. They are not expressed but they are tacitly implied, and are therefore termed ``implied warranty``, which are warranty of seaworthiness of ship and warranty of legality. The implied warranty of seaworthiness is a warranty which is understood by law to exist in the contract without being expressly stated. In this paper, a new approachment was made in respect of the warranty of seaworthiness : that is cargoworthiness of the ship, particularly focused on the reasonable fitness to carry the good or other movables to the destination contemplated by the policy, which is concerned with her capability to carry the particular cargo in question, commonly referred to as the cargoworthiness under Article 40(2) in Maritime Insurance Act, 1906. In the event of a breach of warranty, the insurer is discharged from liability as from the date of the breach. However, the breach of warranty does not inevitably discharge the insurer from liability, for it is always open to an insurer to waive the breach and therby affirm the continuance of the contract. An insurer can certainly, by his conduct, be estopped from pleading as having been discharged from liability under the Seaworthiness Admitted Clause and Unseaworthiness & Unfitness Exclusion Clause in the Institute Cargo Clauses. It is conclusion of this paper that in the present time, the insurance warranty, especially the implied warranty for the seaworthiness of the assured would be complied with not strictly but with flexibility, and the limitation of an insurer`s right of the breach of the warranty.