Provided is a DDoS attack detection apparatus including an information collecting unit to collect DDoS detection information including rate information about traffic change, variation of a first type flow and a Packet Per Second (PPS) for a second type flow, in which the rate information about traffic change is obtained using packet count of packets input per a unit time, flow count of flows input per the unit time and the byte count of bytes input per the unit time; and a testing unit to calculate a probability of occurrence of the DDoS attack by use of a first probability determined by the rate information about traffic change, a second probability determined by the variation of the first type flow and a third probability determined by the PPS for the second type flow and detect occurrence of the DDoS attack based on the probability of occurrence of the DDoS attack.