Disclosed is a planar antenna, including: a film formed of a planar insulating material; an antenna portion which is a planar conductor on the film; and a ground portion which is a conductor to be grounded, wherein the antenna portion comprises: at least one first short stub; a first antenna element which is connected to the ground portion through the at least one first short stub and whose shape has such an angle that a distance between the first antenna element and the ground portion increases with increasing distance from a feeding point along the ground portion, the feeding point being provided between the first antenna element and the ground portion; a second short stub; and a second antenna element which is connected to the first antenna element through the second short stub.