It was passed down to James from his father, Fleamont Potter, making it a family heirloom.
The cloak's true origin is never explicitly revealed, but it is heavily implied to be a powerful and ancient magical artifact.
It's important to note that the cloak is not simply an ordinary invisibility device; it is imbued with a potent magical essence. It was highly valued by both James and Fleamont, suggesting its importance and possibly its unique properties beyond just making the wearer invisible.