An antenna unit operating for two frequency bands either when contained or pulled out. A fixed antenna unit 20 and a slide antenna unit 30 are provided. A helical antenna 21 is provided in the fixed antenna unit 20. A first monopole antenna 31 having the same axis as the helical antenna 21, a second monopole antenna 32, and an antenna cover 33 for holding the second monopole antenna 32 on the extended axis of the first monopole antenna 31 are provided in the slide antenna unit 30. The first monopole antenna 31 is held at the position where is not electromagnetically connected to the helical antenna 21 when the slide antenna unit 30 is pulled out, and the second monopole antenna 32 is held at the position where it is electromagnetically connected to the helical antenna 21. Further, the first monopole antenna 31 is held at the position where is electromagnetically connected to the helical antenna 21, and the second monopole antenna 32 is held at the position where is not electromagnetically connected to the helical antenna 21.