A monitoring system of an embodiment includes an acquirer, an extractor, an encryption processor, and a generator. The acquirer is configured to acquire, from one or more monitoring cameras that capture an image of a work area in which presented information to be input is input to an input terminal, a captured image captured by the one or more monitoring cameras. The extractor is configured to extract the information to be input from the captured image acquired by the acquirer. The encryption processor is configured to encrypt the information to be input extracted by the extractor. The generator is configured to generate a replaced image in which the information to be input is made invisible, the replaced image comprising a partial image that displays information encrypted by the encryption processor at a position of the information to be input in the captured image acquired by the acquirer.