A window plate mountable to an opening of a vehicle body, the window plate comprising a monopolar vehicle antenna for receiving a vertical polarized wave, the vehicle antenna comprising: a first antenna conductor (α); and a power-feed part including a first connection point (a); wherein the first antenna conductor (α) and the power-feed part are configured to be positioned in a vicinity of an upper edge part of the opening and arranged between a side edge part of the opening and a center line of the window plate in a width direction of the window plate, wherein the first antenna conductor (α) includes a first linear element extending in a vertical direction and including upper and lower ends, the upper end being directly connected to the first connection point (a) or connected to the first connection point (a) by way of a connection element extending in a horizontal direction, a second linear element extending in a horizontal direction and connected to the first linear element at the lower end or a vicinity of the lower end, and a third linear element directly connected to the first connection point (a) and extending in a horizontal direction, or connected to an end part (e) of the connection element and extending in a horizontal direction linearly from the end part (e) of the connection element so that the third linear element and the connection element constitute a coupling element, wherein a length of the second linear element is greater than a length of the first linear element, wherein, when a wavelength of a radio wave transmitted in an air in a central frequency of a first frequency band is λ 01, a wavelength shortening rate of the window plate is k, and a wavelength on the window plate is λ g1 =λ 01 •k, a length of longest path from the power-feed part to a tip of the second linear element is greater than or equal to (3/16)·λ g1 and less than or equal to (11/32)•λ g1, characterized in that the third linear element and the second linear element are configured to create a capacitive coupling. a first antenna conductor (α); and a power-feed part including a first connection point (a); wherein the first antenna conductor (α) and the power-feed part are configured to be positioned in a vicinity of an upper edge part of the opening and arranged between a side edge part of the opening and a center line of the window plate in a width direction of the window plate, wherein the first antenna conductor (α) includes a first linear element extending in a vertical direction and including upper and lower ends, the upper end being directly connected to the first connection point (a) or connected to the first connection point (a) by way of a connection element extending in a horizontal direction, a second linear element extending in a horizontal direction and connected to the first linear element at the lower end or a vicinity of the lower end, and a third linear element directly connected to the first connection point (a) and extending in a horizontal direction, or connected to an end part (e) of the connection element and extending in a horizontal direction linearly from the end part (e) of the connection element so that the third linear element and the connection element constitute a coupling element, a first linear element extending in a vertical direction and including upper and lower ends, the upper end being directly connected to the first connection point (a) or connected to the first connection point (a) by way of a connection element extending in a horizontal direction, a second linear element extending in a horizontal direction and connected to the first linear element at the lower end or a vicinity of the lower end, and a third linear element directly connected to the first connection point (a) and extending in a horizontal direction, or connected to an end part (e) of the connection element and extending in a horizontal direction linearly from the end part (e) of the connection element so that the third linear element and the connection element constitute a coupling element, wherein a length of the second linear element is greater than a length of the first linear element, wherein, when a wavelength of a radio wave transmitted in an air in a central frequency of a first frequency band is λ 01, a wavelength shortening rate of the window plate is k, and a wavelength on the window plate is λ g1 =λ 01 •k, a length of longest path from the power-feed part to a tip of the second linear element is greater than or equal to (3/16)·λ g1 and less than or equal to (11/32)•λ g1, characterized in that the third linear element and the second linear element are configured to create a capacitive coupling.