A power converter (25, 25b,25d,25e,25g) comprising: a plurality of DC/DC converters (30, 30d,30e,30g); a pair of primary DC terminals (27a, 27b); and a pair of secondary DC terminals (28a, 28b), wherein the plurality of DC/DC converters (30, 30d, 30e, 30g) each include a primary terminal (31a, 31b), a DC/AC conversion circuit (33, 33d) connected to the primary terminal (31a, 31b), a transformer (1, 1a, 1b, 1c), an AC/DC conversion circuit (34, 34d), and a secondary terminal (32a, 32b) connected to the AC/DC conversion circuit (34, 34d), characterised in that the transformer (1, 1a, 1b, 1c) includes a first core, a first primary coil, the first primary coil including a first conductor wound around the first core, a first secondary coil, the first secondary coil including a second conductor (17, 18) wound around the first core, and a first insulating member covering the first secondary coil, wherein the first secondary coil is applied with a high voltage compared with the first primary coil, and the second conductor (17, 18) has a shape of a first polygon in a first cross-section of the second conductor (17, 18) perpendicular to a direction in which the second conductor (17, 18) extends, and a first corner of the first polygon has a first radius of curvature of 0.1 mm or more. a plurality of DC/DC converters (30, 30d,30e,30g); a pair of primary DC terminals (27a, 27b); and a pair of secondary DC terminals (28a, 28b), wherein the plurality of DC/DC converters (30, 30d, 30e, 30g) each include a primary terminal (31a, 31b), a DC/AC conversion circuit (33, 33d) connected to the primary terminal (31a, 31b), a transformer (1, 1a, 1b, 1c), an AC/DC conversion circuit (34, 34d), and a secondary terminal (32a, 32b) connected to the AC/DC conversion circuit (34, 34d), a primary terminal (31a, 31b), a DC/AC conversion circuit (33, 33d) connected to the primary terminal (31a, 31b), a transformer (1, 1a, 1b, 1c), an AC/DC conversion circuit (34, 34d), and a secondary terminal (32a, 32b) connected to the AC/DC conversion circuit (34, 34d), characterised in that the transformer (1, 1a, 1b, 1c) includes a first core, a first primary coil, the first primary coil including a first conductor wound around the first core, a first secondary coil, the first secondary coil including a second conductor (17, 18) wound around the first core, and a first insulating member covering the first secondary coil, wherein the first secondary coil is applied with a high voltage compared with the first primary coil, and the transformer (1, 1a, 1b, 1c) includes a first core, a first primary coil, the first primary coil including a first conductor wound around the first core, a first secondary coil, the first secondary coil including a second conductor (17, 18) wound around the first core, and a first insulating member covering the first secondary coil, wherein the first secondary coil is applied with a high voltage compared with the first primary coil, and the second conductor (17, 18) has a shape of a first polygon in a first cross-section of the second conductor (17, 18) perpendicular to a direction in which the second conductor (17, 18) extends, and a first corner of the first polygon has a first radius of curvature of 0.1 mm or more.