A coil device comprises a bobbin structure, three or more pin lines and two or more coils. The bobbin structure comprises a body section, a first flange section and a second flange section. The body section is positioned between the first flange section and the second flange section in a first horizontal direction. The first flange section comprises a first lower base and a first upper portion. The first upper portion extends upwardly from the first lower base. The first upper portion is provided with a first upper edge on which at least one guide recess is formed. The second flange section comprises a second lower base and a second upper portion. The second lower base faces the first lower base in the first horizontal direction. The second upper portion extends upwardly from the second lower base. The second upper portion faces the first upper portion in the first horizontal direction with the body section interposed therebetween. Each of the pin lines consists of two or more pins arranged in a second horizontal perpendicular to the first horizontal direction. Two or more of the pin lines extend downwardly from the first lower base. One or more of the pin lines extends downwardlyfrom the second lower base. Each of coils comprises a wrapped portion and two twisted portions extending from the wrapped portion. The wrapped portions of the coils are wrapped around the body section of the bobbin structure so that the coils have their axes extending along the first horizontal direction. Each of the twisted portions is twisted around one of the pins. At least one of the twisted portions is guided by the at least one guide recess and extends over the first upper edge to a corresponding one of the pins.