Exhibit 5.1

November 15, 2011

Board of Directors

Hanmi Financial Corporation

3660 Wilshire Boulevard, Penthouse Suite A

Los Angeles, California 90010

Ladies and Gentlemen:

We have acted as counsel to Hanmi Financial Corporation, a Delaware corporation (the “Company”), in connection with the Company’s Registration Statement on Form S-3 (File No. 333-163206), originally filed with the U.S. Securities and Exchange Commission (the “Commission”) on November 19, 2009 and declared effective by the Commission on November 30, 2009, under the Securities Act of 1933, as amended (the “Securities Act”), and the Company’s Registration Statement on Form S-3 (File No. 333-177996) filed with the Commission pursuant to Rule 462(b) under the Securities Act on November 15, 2011 (collectively, the “Registration Statement”). Pursuant to a prospectus supplement (the “Prospectus Supplement”) filed with the Commission on November 15, 2011, and the related Prospectus (the “Prospectus”) included in the Registration Statement, the Company is specifying for offering and take-down (the “Take-down”) up to 100,625,000 shares of the Company’s common stock, $0.001 par value per share (the “Common Stock”). We have been requested by the Company to render this opinion in connection with the Take-down.

In rendering our opinion, we have reviewed the Registration Statement and the exhibits thereto, the Prospectus and the Prospectus Supplement. We have also reviewed such corporate documents and records of the Company, such certificates of public officials and such other matters as we have deemed necessary or appropriate for purposes of this opinion. We have relied, as to any questions of fact upon which our opinion is predicated, upon representations and certificates of the officers of the Company.

We have assumed that all documents referenced herein are the valid and binding obligations of and enforceable against the parties thereto. We have also assumed the authenticity of all documents submitted to us as originals, the genuineness of all signatures, the conformity to authentic original documents of all documents submitted to us as certified, conformed or photostatic copies and the legal capacities of all natural persons.

Based on the foregoing, and subject to the assumptions, limitations and qualifications set forth herein, we are of the opinion that upon issuance and delivery of, and payment for, the shares of Common Stock in the manner contemplated by the Registration Statement, the Prospectus and the Prospectus Supplement, the shares of Common Stock will be validly issued, fully paid and non-assessable.

This opinion is limited solely to the federal laws of the United States and the General Corporation Law of the State of Delaware, and we express no opinion as to the effect on the

GREENBERG TRAURIG, LLP n ATTORNEYS AT LAW n WWW.GTLAW.COM

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Board of Directors

Hanmi Financial Corporation

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matters covered by this opinion letter of the laws of any other jurisdiction. We are not rendering any opinion as to compliance with any federal or state antifraud law, rule or regulation relating to securities, or to the sale or issuance thereof.

This opinion is rendered as of the date hereof, and we assume no obligation to advise you of changes in law or fact (or the effect thereof on the opinions expressed herein) that hereafter may come to our attention. This opinion is to be used only in connection with the offer and sale of the Common Stock while the Registration Statement is effective. This opinion is rendered to you and for your benefit solely in connection with the Registration Statement and the Take-down. This opinion may not be relied on by you for any other purpose.

We hereby consent to the use of our name in the Prospectus Supplement as attorneys who passed upon the legality of the shares of Common Stock and to the filing of a copy of this opinion as an exhibit to the Registration Statement. By giving such consent, we do not hereby admit that we are an “expert” within the meaning of the Act. This opinion should not be quoted in whole or in part without the prior written consent of this firm, nor is this opinion letter to be filed with or furnished to any other governmental agency or other person, except as otherwise required by law.