An antenna device includes: a ground plane having an edge; a matching circuit; and a T-shaped antenna element including a first element and a second element extending from a feed point to a first and second end parts. The first element has a resonance frequency that is higher than a first frequency. The second element has a resonance frequency between a second frequency and a third frequency. A first value obtained by dividing a length from a corresponding point to a first bend part by the first wavelength is less than or equal to a second value obtained by dividing a length from the corresponding point to a second bend part by the second wavelength. An imaginary component of an impedance of the matching circuit takes a positive value at the first frequency and the second frequency and takes a negative value at the third frequency.