Edge extracting method and apparatus using a neural network performing a function of diffusing an excitation. The method and apparatus continuously detect a variety of intensity changes of an image via a function having a variety of frequency characteristics. An edge of a fixed object is detected from images continuously input, and an edge of a moving object is selectively detected from the images. The edge extracting apparatus includes a first neural network which receives an image signal. The first neural network derives a Gaussian function representing the regularity of an excitatory response and an inhibitory response to a spot excitation of the image signal. The apparatus also includes a second neural network which detects edges of an image represented by the image signal by convolving the Gaussian function and the image signal.