noun
guarantor; surety; sponsor; reference
A person who guarantees another's obligations, such as a loan, lease, or contract. Often required in rental agreements and financial transactions.
アパートを借りるときは保証人が必要です。
When renting an apartment, a guarantor is required.
彼は私のローンの保証人になってくれた。
He became the guarantor for my loan.