Alzheimer's disease is a progressive degenerative disease of the brain marked by gradual and irreversible declines in cognitive functions. Acetylcholinesterase (AChE) plays a biological role in the termination of nerve impulse transmissions at cholinergic synapses by rapid hydrolysis of its substrate, "acetylcholine". The deficit level of acetylcholine leads to deprived nerve impulse transmission. Thus the cholinesterase inhibitors would reverse the deficit in acetylcholine level and consequently may reverse the memory impairments, which is characteristic of the Alzheimer's disease. The molecular interactions between AChE and Carnosic acid, a well known antioxidant substance found in the leaves of the rosemary plant has always been an area of interest. Here in this study we have performed in silico approach to identify carnosic acid derivatives having the potential of being a possible drug candidate against AChE. The best candidates were selected on the basis of the results of different scoring functions.