An object detection method performed by a movable device is provided. The object detection method includes emitting radio frequency signals, receiving radio frequency signals reflected by an object, obtaining N sample sequences by digitizing N radio frequency signals, N being a natural number greater than or equal to 2, from among the received radio frequency signals, obtaining a matrix including each of the N sample sequences as a column, in an order in which the radio frequency signals are received, obtaining a resulting signal by summing samples for each row of the matrix and obtaining an energy value from the resulting signal, and detecting the object based on the obtained energy value being greater than or equal to a certain threshold value.