We developed a new observation system "WIZARD"; Wide-field Imager of Zodiacal light with Array Detector. Since the zodiacal light is faint and very extended all over the sky, WIZARD employs a sensitive CCD with a wide field optics with sufficient spatial resolution to remove the contribution of integrated flux of individual stars. WIZARD is designed to measure the absolute brightness of the diffuse sky at visible wavelength and to have good stability of the instrumental zero-level and low noise feature. The first light of WIZARD was performed in 2001 at Mauna Kea, Hawaii, and the first scientific image of the gegenschein was taken in 2002 under collaboration with SUBARU observatory. We have been promoting extended observations of the zodiacal light along the ecliptic plane. The design and the performance of WIZARD system, and also the preliminary results of the zodiacal light observations are introduced in this paper.