Guitar Pro allows to export GP files to MIDI. But I need to convert very many GP files to MIDI. So is there any tool to do it in batch?
Answer: No. Guitar Pro uses a proprietary format so only Arobas Music could to that and they didn't.
Workaround: What you can do is to create a macro script (in AutoHotkey for example) that open the files on the desired folder for you using the Guitar Pro "open file dialog" then click the "export to midi" feature.