A capacitor includes a metallic tantalum, an electrical conductor, and a tantalum oxide film. The tantalum oxide film is disposed in contact with the metallic tantalum and between the metallic tantalum and the electrical conductor. The tantalum oxide film includes a first portion and a second portion. The first portion contains fluorine. The second portion is located closer to the metallic tantalum than the first portion in a thickness direction of the tantalum oxide film. In the tantalum oxide film, a fluorine concentration in the second portion is lower than a fluorine concentration in the first portion. A ratio d1/d0 of a thickness d1 of the first portion to a thickness d0 of the tantalum oxide film is more than 0.4 and 0.8 or less.