An antenna device, in which a dipole antenna (110), a first monopole antenna, and a second monopole antenna are disposed on an insulating board (140), wherein the dipole antenna (110) includes left and right elements connected to a power feeding section (150), and the left and right elements have: first portions extended from the power feeding section in a state of facing each other; and second portions extended from the first portions separately to left and right sides, and the first monopole antenna (120) connects to the power feeding section and extends toward the second portion of the left element in the dipole antenna (110), and the second monopole antenna (130) connects to the power feeding section (150) and extended toward the second portion of the right element of the dipole antenna (110).