NEW MATERIAL:4-aminopyridine derivative expressed by formula I or acid- added salt of said derivative (R1 is H, hydroxyl group, lower alkoxy, morpholino or -NH-B, etc.; B is lower alkyl, cycloalkyl or phenyl; R2 and R3 are H, lower alkyl, lower alkylcarbonyl, or the two join and containing N to form azacycloalkyl or morpholino, etc.; R4 and R5 are H, or join to form quinoline ring or 5,6,7,8-tetrahydroquinoline ring together with ring A, with a proviso that for a case of R1, R4 and R5 are equally H, the case that R2 and R3 are equally H, or equally methyl, is excepted. For a case that R1 is H; R4 and R5 join to form quinoline ring together with the ring A, the case that R2 and R3 are equally H or ethyl, is excepted).

USE: Useful as a remedy for Alzheimer-type dementia.

PREPARATION: A compound expressed by formula II (RA and RB are H, etc.) is reacted with enamine corresponding to the aimed compound to afford the compound expressed by formula I.