The present invention provides a novel indoline derivative or a pharmacologically acceptable salt thereof or a solvate of the derivative or a salt thereof represented by the following formula (1) that has an excellent butyrylcholinesterase inhibitory activity. In the formula, R1 represents an alkyl group, a cycloalkyl group, a heterocycloalkyl group, an aryl group, a heteroaryl group, an arylalkyl group, a heteroarylalkyl group, a cycloalkylalkyl group, a heterocycloalkylalkyl group, a dihydrofurylalkyl group, an alkenyl group, a tetrahydronaphthyl group, or an indanyl group; R2 represents a hydrogen atom, an alkyl group, an arylalkyl group, a cycloalkylalkyl group, a heteroarylalkyl group, a heterocycloalkylalkyl group, an aryl group, or an acyl group; R3 each independently represents a hydrogen atom, an alkyl group, or a dialkylaminocarbonyl group; R4 each independently represents a hydrogen atom or an alkyl group; and R5 represents a hydrogen atom or an alkyl group. Each functional group may have a substituent.