A detection apparatus is provided. The detection apparatus includes a hardware processor programmed to at least calculate a first echo intensity of a first reception signal generated from a reception wave reflected on reflection objects, calculate a second echo intensity of a second reception signal generated from a reception wave reflected on the reflection objects, a signal duration of the second reception signal being shorter than that of the first reception signal, generate a first frequency distribution of the first echo intensity, generate a second frequency distribution of the second echo intensity, and extract a density of the reflection objects or an index of density of the reflection objects based on a comparison of the first frequency distribution and the second frequency distribution.