A millimeter-wave radar cover housing a millimeter-wave radar including an antenna and an electronic circuit configured to drive the antenna , the millimeter-wave radar cover comprising: a first site (A) provided in front of the millimeter-wave radar to protect the millimeter-wave radar and transmit millimeter electromagnetic waves emitted from the antenna ; and a second site (B) including a housing space in which the antenna and the electronic circuit except for the first site (A) are housed, wherein the first site (A) is made of a stacked structural body obtained by stacking at least one layer of a first constituent material having a negative relative permittivity in the frequency band of the millimeter waves and a second constituent material having a positive relative permittivity in the frequency band of the millimeter waves, the first constituent material is formed in a lattice shape by a conductive material, and the structural body formed when the first constituent material is stacked with the second constituent material , has a relative permittivity and a relative permeability equal to each other for the frequency band of the millimeter waves, and the stacked structural body has an effective transmissivity close to one for the frequency band of the millimeter waves, and an effective transmissivity close to zero for a frequency band equal to or lower than 1 GHz, which is lower than the frequency band of the millimeter waves, the frequency band of the millimeter wave band is set in the range of 76 GHz to 81 GHz, and the first constituent material has the negative relative permittivity in the frequency band of the millimeter waves by a restricted number of conduction electrons. a first site (A) provided in front of the millimeter-wave radar to protect the millimeter-wave radar and transmit millimeter electromagnetic waves emitted from the antenna ; and a second site (B) including a housing space in which the antenna and the electronic circuit except for the first site (A) are housed, wherein the first site (A) is made of a stacked structural body obtained by stacking at least one layer of a first constituent material having a negative relative permittivity in the frequency band of the millimeter waves and a second constituent material having a positive relative permittivity in the frequency band of the millimeter waves, the first constituent material is formed in a lattice shape by a conductive material, and the structural body formed when the first constituent material is stacked with the second constituent material , has a relative permittivity and a relative permeability equal to each other for the frequency band of the millimeter waves, and the stacked structural body has an effective transmissivity close to one for the frequency band of the millimeter waves, and an effective transmissivity close to zero for a frequency band equal to or lower than 1 GHz, which is lower than the frequency band of the millimeter waves, the frequency band of the millimeter wave band is set in the range of 76 GHz to 81 GHz, and the first constituent material has the negative relative permittivity in the frequency band of the millimeter waves by a restricted number of conduction electrons. <EOS>