Quinazoline derivatives following novel, are useful as pesticides. The following formula [I]: Wherein, n is an integer of 0~4, R 1 represents phenyl, etc., R 2 represents a hydrogen atom, R 3 represents methyl, benzyl or the like, a hydrogen atom, R 4 is fluorine atom I represent. ]下記の新規なキナゾリン誘導体は、有害生物防除剤として有用である。次式[I]:[式中、nは0~4の整数を表し、R1はフェニル等を表し、R2は水素原子等を表し、R3はメチル、ベンジル等を表し、R4は水素原子、フッ素原子等を表す。]