A vehicular washing device (1; 1A) comprising: a nozzle (4; 4A) configured to spray a fluid toward an object to be washed; a flow passage forming body (2; 2A) of which an internal space is a flow passage of the fluid; and a valve (21; 21A; 21B) that has a pressing tube part with an axial direction coinciding with a flow direction of the fluid, is elastically deformable in a direction in which a diameter of the pressing tube part changes, and configured to open and close the flow passage according to a state of deformation, wherein: a first flow passage and a second flow passage are formed as the flow passage on opposite sides of the pressing tube part; a shaft with which the pressing tube part is capable of coming into close contact is located inside the valve (21; 21A; 21B); and the valve (21; 21A; 21B) is configured to deform elastically according to a magnitude of a pressure of the first flow passage or a pressure of the second flow passage relative to an atmospheric pressure; the vehicular washing device being characterized in that: the valve (21; 21A; 21B) is provided with a first inclined part and a second inclined part that are continuous with both ends of the pressing tube part in the axial direction; and a diameter of each of the first inclined part and the second inclined part decreases toward the pressing tube part in the axial direction. a nozzle (4; 4A) configured to spray a fluid toward an object to be washed; a flow passage forming body (2; 2A) of which an internal space is a flow passage of the fluid; and a valve (21; 21A; 21B) that has a pressing tube part with an axial direction coinciding with a flow direction of the fluid, is elastically deformable in a direction in which a diameter of the pressing tube part changes, and configured to open and close the flow passage according to a state of deformation, wherein: a first flow passage and a second flow passage are formed as the flow passage on opposite sides of the pressing tube part; a shaft with which the pressing tube part is capable of coming into close contact is located inside the valve (21; 21A; 21B); and the valve (21; 21A; 21B) is configured to deform elastically according to a magnitude of a pressure of the first flow passage or a pressure of the second flow passage relative to an atmospheric pressure; the vehicular washing device being characterized in that: the valve (21; 21A; 21B) is provided with a first inclined part and a second inclined part that are continuous with both ends of the pressing tube part in the axial direction; and a diameter of each of the first inclined part and the second inclined part decreases toward the pressing tube part in the axial direction. a first flow passage and a second flow passage are formed as the flow passage on opposite sides of the pressing tube part; a shaft with which the pressing tube part is capable of coming into close contact is located inside the valve (21; 21A; 21B); and the valve (21; 21A; 21B) is configured to deform elastically according to a magnitude of a pressure of the first flow passage or a pressure of the second flow passage relative to an atmospheric pressure; the vehicular washing device being characterized in that: the valve (21; 21A; 21B) is provided with a first inclined part and a second inclined part that are continuous with both ends of the pressing tube part in the axial direction; and a diameter of each of the first inclined part and the second inclined part decreases toward the pressing tube part in the axial direction. the valve (21; 21A; 21B) is provided with a first inclined part and a second inclined part that are continuous with both ends of the pressing tube part in the axial direction; and a diameter of each of the first inclined part and the second inclined part decreases toward the pressing tube part in the axial direction.