A wideband dual-mode complementary dipole antenna is proposed. The antenna is composed of a wideband slotline radiator and an electric dipole. It is excited by a coaxial cable at the center. A pair of slot stubs is used to perturb the second odd-order mode within the slotline radiator, and a dual-resonant wideband radiation characteristic is resulted in. An antenna prototype is then designed, fabricated and measured. The measured results show the antenna has a fractional impedance bandwidth of 40.2% with two resonances. Unidirectional radiation pattern and an average gain of about 7 dBi are satisfactorily achieved within the operating bandwidth as well. The antenna has a simple structure and exhibits a dual-resonant, wideband radiation characteristic.