Provided are a method for producing a graphite oxide derivative capable of simply producing a high-quality graphite oxide derivative, and a high-quality graphite oxide derivative. The present invention relates to a method for producing a graphite oxide derivative, the method including the steps of oxidizing graphite; and preparing a graphite oxide derivative by reacting graphite oxide in a reaction liquid containing graphite oxide obtained in the oxidation step or graphite oxide in a graphite oxide-containing composition that is separated from the reaction liquid with a compound reactive with an oxygen-containing functional group of the graphite oxide, the method not including the step of purifying and drying the graphite oxide-containing reaction liquid between the oxidation step and the graphite oxide derivative preparation step.