The present invention relates to a P2P loan service system of an online personal bank and a method thereof which establish an online personal bank for providing a P2P loan service by using an application of a PC, a smartphone or a tablet PC, accumulate investment money of investors in a fintech market of an online personal bank to provide a P2P loan to a loan applicant, attract investment after writing an investment contract through crowd funding from a plurality of investors holding deposits/savings, stocks, real estate and bonds through media promotion, website marketing and blog marketing, allow an online personal bank or an investor to directly deposit loan money to a loan applicant after writing a loan contract, manage information of the loan applicant by the online personal bank, allow the investor to take an interest and the principal through the online personal bank wherein the interest is based on an interest rate for loan money of a borrower and the principal is money when a loan expires, and provide a principal guarantee insurance service for guaranteeing the principal of investors in case of crowd funding of the investors to the online personal bank to provide P2P loan services, thereby creating profits of the online personal bank which provides P2P loan services from a person to a company, from a company to a person and from a person to a person.(AA) Person to person.(BB) Company to person(CC) Person to company, (DD) Loan service(EE) Loan(FF) Loan applicant(GG) Registration(HH) Neobank financial intermediation platform(II) Promotion(JJ) Investors(KK) Interest payment(LL) Neobank loan service : if the loan applicant registers in the Neobank, the loan applicant may be able to promote and attract investment to a large number of investors through Neobank and the investors may make their loan decisions with reference to them. Then, the investors may receive interest and principal from the loan applicant by the loan expiration date.COPYRIGHT KIPO 2018