A helmet including an exterior member and an interior member (A) and provided with a head-up display device , wherein a liner and a mouth cover are disposed inside the exterior member and constitute the interior member (A), the head-up display device includes a projection unit configured to project display light to a projection target, the display light being used for forming a display image capable of being visually recognized as a virtual image by a user wearing the helmet through the projection target, the projection target being disposed in front of an eye (E) of the user and having both light transmittance and light reflection, the projection unit includes a light emitter configured to emit display light, a housing having an opening through which display light emitted from the light emitter passes, and a cover member having transparency to light and disposed to cover the opening of the housing , a cylindrical optical path portion is provided at a side of the housing having the opening , the projection unit is incorporated in a chin portion of the helmet such that display light to be projected to the projection target through the cover member passes through the cylindrical optical path portion provided in the interior member (A), and the cover member is disposed at an inner side of the interior member (A) rather than on a surface of the interior member (A) at which an end of the cylindrical optical path portion at a light emission side is open such that the cover member is located at a deep position in the interior member (A) and when the user holds a chin portion in using the helmet , fingers of the user do not easily touch the cover member . a liner and a mouth cover are disposed inside the exterior member and constitute the interior member (A), the head-up display device includes a projection unit configured to project display light to a projection target, the display light being used for forming a display image capable of being visually recognized as a virtual image by a user wearing the helmet through the projection target, the projection target being disposed in front of an eye (E) of the user and having both light transmittance and light reflection, the projection unit includes a light emitter configured to emit display light, a housing having an opening through which display light emitted from the light emitter passes, and a cover member having transparency to light and disposed to cover the opening of the housing , a cylindrical optical path portion is provided at a side of the housing having the opening , the projection unit is incorporated in a chin portion of the helmet such that display light to be projected to the projection target through the cover member passes through the cylindrical optical path portion provided in the interior member (A), and the cover member is disposed at an inner side of the interior member (A) rather than on a surface of the interior member (A) at which an end of the cylindrical optical path portion at a light emission side is open such that the cover member is located at a deep position in the interior member (A) and when the user holds a chin portion in using the helmet , fingers of the user do not easily touch the cover member . <EOS>