In a signal detection apparatus, power detection section 101 detects power of an inputted received signal, and upon detection of power exceeding a power detection threshold, outputs a trigger to storage section 102. Storage section 102 stores a first received signal upon reception of the trigger and outputs the stored first received signal to multiplier 103 and newly stores a second received signal upon receipt of the next trigger. Multiplier 103 multiplies the second received signal by the first received signal, integrator 104 integrates the multiplication result from multiplier 103 during a predetermined duration to obtain a correlation value of the second and first received signals, and absolute value calculation section 105 calculates an absolute value of the correlation value from integrator 104. Determination section 106 determines the presence/absence of a detection-target signal based on the absolute value of the correlation value from absolute value calculation section 105.