    <SEC-DOCUMENT>0001133228-25-007664-index.html : 20250729
    <SEC-HEADER>0001133228-25-007664.hdr.sgml : 20250729
    <ACCEPTANCE-DATETIME>20250729083734
    ACCESSION NUMBER:		0001133228-25-007664
    CONFORMED SUBMISSION TYPE:	N-CSRS
    PUBLIC DOCUMENT COUNT:		9
    CONFORMED PERIOD OF REPORT:	20250531
    FILED AS OF DATE:		20250729
    DATE AS OF CHANGE:		20250729
    EFFECTIVENESS DATE:		20250729

    FILER:

    	COMPANY DATA:
    		COMPANY CONFORMED NAME:			Western Asset Investment Grade Opportunity Trust Inc.
    		CENTRAL INDEX KEY:			0001462586
    		ORGANIZATION NAME:
    		EIN:				000000000
    		STATE OF INCORPORATION:			MD
    		FISCAL YEAR END:			1130

    	FILING VALUES:
    		FORM TYPE:		N-CSRS
    		SEC ACT:		1940 Act
    		SEC FILE NUMBER:	811-22294
    		FILM NUMBER:		251157782

    	BUSINESS ADDRESS:
    		STREET 1:		620 EIGHTH AVENUE
    		STREET 2:		47TH FLOOR
    		CITY:			NEW YORK
    		STATE:			NY
    		ZIP:			10018
    		BUSINESS PHONE:		888-777-0102

    	MAIL ADDRESS:
    		STREET 1:		620 EIGHTH AVENUE
    		STREET 2:		47TH FLOOR
    		CITY:			NEW YORK
    		STATE:			NY
    		ZIP:			10018

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	Western Asset Investment Grade Defined Opportunity Trust Inc.
    		DATE OF NAME CHANGE:	20090423
    </SEC-HEADER>
    <DOCUMENT>
    <TYPE>N-CSRS
    <SEQUENCE>1
    <FILENAME>waigoti-efp16604_ncsrs.htm
    <DESCRIPTION>WESTERN ASSET INVESTMENT GRADE OPPORTUNITY TRUST INC - N-CSRS
    <TEXT>
    Document 1 - file: waigoti-efp16604_ncsrs.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.CERT
    <SEQUENCE>2
    <FILENAME>waigoti-efp16604_ex99cert.htm
    <DESCRIPTION>CERTIFICATIONS PURSUANT TO SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002
    <TEXT>
    Document 2 - file: waigoti-efp16604_ex99cert.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.906 CERT
    <SEQUENCE>3
    <FILENAME>waigoti-efp16604_ex99906cert.htm
    <DESCRIPTION>CERTIFICATIONS PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002
    <TEXT>
    Document 3 - file: waigoti-efp16604_ex99906cert.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>4
    <FILENAME>img1ad90c3c5.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 4 - file: img1ad90c3c5.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>5
    <FILENAME>img017b40752.gif
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 5 - file: img017b40752.gif

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>6
    <FILENAME>img50c8ce681.gif
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 6 - file: img50c8ce681.gif

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>7
    <FILENAME>img65a447e24.gif
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 7 - file: img65a447e24.gif

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>8
    <FILENAME>img70b96eea6.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 8 - file: img70b96eea6.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>9
    <FILENAME>img18553da63.gif
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 9 - file: img18553da63.gif

    </DOCUMENT>
    </SEC-DOCUMENT>