A dipole antenna used in an operation frequency includes a dipole radiation main body, a first semi-loop metal line and a second semi-loop metal line is provided. The dipole radiation main body has a first radiation line arm and a second radiation line arm aligned in a straight line, wherein a gap exists therebetween to form a feeding terminal. The first semi-loop metal line has two ends respectively connected to the first radiation line arm and the second radiation line arm to form a first matching loop covering the feeding terminal. The second semi-loop metal line has two ends respectively connected to the first radiation line arm and the second radiation line arm to form a second matching loop, which is larger than the first matching loop.