A common mode choke coil, comprising: a first coil portion and a second coil portion that are connected in series to each other between a first terminal and a second terminal; and a third coil portion and a fourth coil portion that are connected in series to each other between a third terminal and a fourth terminal, the four coil portions being respectively disposed in four quadrants of an orthogonal coordinate system, and an annular core passing through inner spaces of the four coil portions, wherein the first coil portion and the second coil portion are respectively disposed in a first quadrant and a third quadrant of the orthogonal coordinate system and housed in a first bobbin, and the third coil portion and the fourth coil portion are respectively disposed in a fourth quadrant and a second quadrant of the orthogonal coordinate system and housed in a second bobbin, the first bobbin includes a pair of rectangular cylindrical case portions (81,82) that house the first coil portion and the second coil portion, a coupling portion that diagonally couples the pair of case portions and that extends to a middle in a height direction of the case portions, and a recess portion that is continuous with the coupling portion and that is formed between corners of the case portions that are adjacent to each other, the second bobbin includes a pair of rectangular cylindrical case portions (83,84) that house the third coil portion and the fourth coil portion, a coupling portion that diagonally couples the pair of case portions and that extends to a middle in a height direction of the case portions, and a recess portion that is continuous with the coupling portion and that is formed between corners of the case portions that are adjacent to each other, and the first bobbin and the second bobbin are coupled by fitting the coupling portion of one of the bobbins to the recess portion of the other bobbin, the pair of case portions of the first bobbin are disposed in the first quadrant and the third quadrant of the orthogonal coordinate system, and the pair of case portions of the second bobbin are disposed in the fourth quadrant and the second quadrant of the orthogonal coordinate system. a first coil portion and a second coil portion that are connected in series to each other between a first terminal and a second terminal; and a third coil portion and a fourth coil portion that are connected in series to each other between a third terminal and a fourth terminal, the four coil portions being respectively disposed in four quadrants of an orthogonal coordinate system, and an annular core passing through inner spaces of the four coil portions, wherein the first coil portion and the second coil portion are respectively disposed in a first quadrant and a third quadrant of the orthogonal coordinate system and housed in a first bobbin, and the third coil portion and the fourth coil portion are respectively disposed in a fourth quadrant and a second quadrant of the orthogonal coordinate system and housed in a second bobbin, the first bobbin includes a pair of rectangular cylindrical case portions (81,82) that house the first coil portion and the second coil portion, a coupling portion that diagonally couples the pair of case portions and that extends to a middle in a height direction of the case portions, and a recess portion that is continuous with the coupling portion and that is formed between corners of the case portions that are adjacent to each other, the second bobbin includes a pair of rectangular cylindrical case portions (83,84) that house the third coil portion and the fourth coil portion, a coupling portion that diagonally couples the pair of case portions and that extends to a middle in a height direction of the case portions, and a recess portion that is continuous with the coupling portion and that is formed between corners of the case portions that are adjacent to each other, and the first bobbin and the second bobbin are coupled by fitting the coupling portion of one of the bobbins to the recess portion of the other bobbin, the pair of case portions of the first bobbin are disposed in the first quadrant and the third quadrant of the orthogonal coordinate system, and the pair of case portions of the second bobbin are disposed in the fourth quadrant and the second quadrant of the orthogonal coordinate system.