insurance policy; certificate of insurance
Refers to the formal document that serves as proof of an insurance contract, such as a life or non-life insurance policy.
I lost my insurance policy, so I had it reissued.
Please check the details of the insurance policy carefully when signing the contract.
保険証 is a more general term for an insurance card or certificate, often used for health insurance cards. 保険証書 specifically refers to the formal policy document itself.
life insurance policy
Compound of 保険 (insurance) and 証書 (certificate, deed).