The feline, aged about 4 to 6, entered Panchayati Akhara's Ganga Bagh ashram sometime last night, Ranger of Rajaji National Park Mansingh said.
It seems the big cat entered the ashram premises while chasing a prey, he said.
The leopard was spotted in one of the rooms of the ashram by plumbers who had gone there for some work. They informed the authorities.
Police and Forest Department personnel are trying hard to evict the big cat from the ashram.