An antenna apparatus includes a first ground plane (20); a second ground plane (30) having first, second, third and fourth sides, a cutout part, and a slit (40) having an open end (41); a first radiating element (110) having first and second lines, and a feeding point (115); a second radiating element (120) having a third line; and a parasitic element (130) having first and second parasitic lines. A length from the feeding point to an end part of the slit is set to one-half wavelength at a first communication frequency, a total length of a length from an end part of the fourth line to the feeding point, and a length from a ground potential point (38) to an end part of the second parasitic line is set to one-half wavelength at a second communication frequency, and a length of the third line and the fourth line is set to one-quarter wavelength at a third communication frequency.