An image forming apparatus includes a storage device and a control device. The storage device stores a document. The control device includes a processor and functions, through the processor executing a control program, as a character recognizer and a tag generator. The character recognizer analyzes the document stored in the storage device and recognizes characters contained in the document. The tag generator analyzes, based on a recognition result of the character recognizer, a sequence of characters contained in the document and generates a tag expressing a feature of descriptive content of the document.