Provided are an object detection device and system. The object detection device includes an outline image extraction unit, a feature vector calculation unit, and an object judgment unit. The outline image extraction unit extracts an outline image from an input image. The feature vector calculation unit calculates a feature vector from the outline image by using histogram of oriented gradients (HOG) representing a frequency distribution of gradient vectors with respect to pixels of the outline image, and pixel coordinate information varying according to a spatial distribution of the gradient vectors. The object judgment unit judges a target object corresponding to the feature vector with reference to pre-learned data.