A 2-aminoquinazoline derivative represented by formula (I) {wherein R1 represents a hydrogen atom, or the like, R2 represents a hydrogen atom, R3 represents formula (II) [wherein A1 represents formula (III), or the like, R8 represents lower alkyl, or the like, and R9 represents optionally substituted aryl, or the like], R4 represents hydroxy, or the like, and R5 represents optionally substituted aryl, or the like}, or a pharmaceutically acceptable salt thereof is provided.
