For the purpose of sufficiently correcting magnification chromatic aberration by the common optical element at the subsequent stage while aligning the directions of the images of all fields of view, the wide angle optical system (3) has negative (+) and negative (-A second group (7) having a catadioptric optical element (14), and a third group (8), wherein the catadioptric element (14) comprises a first group A first surface (11) on the object side having a transmitting surface (11a) and a first reflecting surface (11b) disposed around the transmitting surface (11a), a second transmitting surface (12a) and a second reflecting surface A second surface (12) on the image side having a first surface (12b) and a second surface (12) on the image side, the second surface (12b) having an apex angle on the object side and disposed between the first surface (11) and the second surface 3 surface (13), and satisfies the following expression.n> p / 2> 90 -k n is the Abbe number of the negative lens (4), p is the Abbe number of the positive lens (5), is the apex angle of the third surface (13), k is the half angle of the chief ray of the smallest angle of view within the side field of view Field angle (0 < k <90 ).全ての視野の像の方向を揃えながら後段の共通の光学素子によって倍率色収差を十分に補正することを目的として、広角光学系(3)は、負および正のレンズ(4,5)を有する負の屈折力の第1群(6)と、反射屈折光学素子(14)を有する第2群(7)と、第3群(8)とを備え、反射屈折光学素子(14)が、第1透過面(11a)およびこの周囲に配置される第1反射面(11b)を有する物体側の第1面(11)と、第2透過面(12a)およびこの周囲に配置される第2反射面(12b)を有する像側の第2面(12)と、第1面(11)および第2面(12)の間に配置され物体側に頂角を有する円錐面状の透過面である第3面(13)とを備え、次式を満たす。νn>νpα/2>90°-θk νnは負レンズ(4)のアッベ数、νpは正レンズ(5)のアッベ数、αは第3面(13)の頂角角度、θkは側方視野内の最小画角の主光線の半画角(0<θk<90°)。
