I Insurance is an agreement between the insurer and the insured, where the insurer provides protection against certain risks in exchange for premiums from the insured. this study discusses the application of the principle of good faith (utmost good faith) in group life insurance by p.t. sutomo agrindo was on behalf of the late martinus rusmanto at p.t. prudential indonesia, as well as the insurer\\\'s responsibility for the rejection of claims on behalf of the late martinus rusmanto. the research method used is normative legal research with an approach to legal principles, especially group life, insurance law, descriptive in nature, secondary data as the main data supported by interviews, data collections methods through literature studies and interviews, analyzed qualitatively and conclusions drawn deductively. the results of the study describe the application of the principle of good faith (utmost good faith) in group life insurance on behalf of the late martinus rusmanto at p.t. prudential indonesia was not implemented because the insured did not provide correct and complete information regarding his health condition in the group insurance closing letter (spak) document, which is a violation of the principle of good faith as regulated in article 251 of the commercial code. the insurer\\\'s responsibility for the rejection of claim on behalf of the late martinus rusmanto at p.t. prudential indonesia is the return of the premium that has been paid, minus the administration fee in accordance with the provisions of article 8 of prudential work life policy number 1000760