is the work experience of an NGO treated as a work experience in iim.

Yes- definitely - it explains how much resposibility a person is capable of apart from other things such as character.
But has to be full time.

Hi, only a full time job within a registered organization is treated as work exp. If you have did a job in NGO, it can be treated as work exp.

no, they don't treat ngo work as work experience