The present invention is a securities transaction system configured to transact securities issued to raise funds for a predetermined business, where the securities are provided with a par value; a redemption date; a guarantee rate which is a ratio of a deposit, to be paid by a guarantor to an investor who is a holder of the securities in a case where the interest of the securities is unable to be paid and/or is in default, to the par value; an interest rate which defines an interest to be periodically paid to the investor, which is defined as a ratio to the par value or a ratio to a non-guaranteed part which is a part obtained by removing the deposit from the par value; and a business profit allocation which is given to the nonguaranteed part and returned to the investor with respect to a profit of the predetermined business.