One embodiment of the present invention is a flexible tube insertion apparatus including a flexible insertion section to be inserted into a subject. The flexible tube insertion apparatus includes an insertion section state detecting device that detects a state of the insertion section necessary for insertion prediction as detection information when the insertion section is inserted into a subject, and at least one circuit that predicts, using the detection information detected by the insertion section state detecting device, a propulsion state of a distal end of the insertion section and a state of the subject when the insertion section is further inserted from the state of the insertion section, and produces an output based on the prediction.