A plug door device comprising: a first swing arm; a second swing arm spaced apart from the first swing arm in a height direction when mounted on a door (220R, 220L); a first pinion attached to a portion of the first swing arm separated from a rotation axis of the first swing arm; a first rack attachable to the door (220R, 220L) and meshed with the first pinion; a second pinion attached to a portion of the second swing arm separated from a rotation axis of the second swing arm; a second rack attachable to the door (220R, 220L) and meshed with the second pinion; an arm connection shaft including a first arm shaft connected to the first swing arm and having an axis coinciding with the rotation axis of the first swing arm, a second arm shaft connected to the second swing arm and having an axis coinciding with the rotation axis of the second swing arm, and a third arm shaft connecting the first arm shaft and the second arm shaft, wherein the arm connection shaft rotates integrally with the first swing arm and the second swing arm to synchronize rotation of the first swing arm and rotation of the second swing arm; and a pinion connection shaft including a first pinion shaft connected to the first pinion and having an axis coinciding with a rotation axis of the first pinion, a second pinion shaft connected to the second pinion and having an axis coinciding with a rotation axis of the second pinion, and a third pinion shaft connecting the first pinion shaft and the second pinion shaft, wherein the pinion connection shaft rotates integrally with the first pinion and the second pinion to synchronize rotation of the first pinion and rotation of the second pinion, wherein the arm connection shaft includes a first universal joint, which connects the first arm shaft and the third arm shaft, and a second universal joint, which connects the second arm shaft and the third arm shaft, and the pinion connection shaft includes a third universal joint, which connects the first pinion shaft and the third pinion shaft, and a fourth universal joint, which connects the second pinion shaft and the third pinion shaft. a first swing arm; a second swing arm spaced apart from the first swing arm in a height direction when mounted on a door (220R, 220L); a first pinion attached to a portion of the first swing arm separated from a rotation axis of the first swing arm; a first rack attachable to the door (220R, 220L) and meshed with the first pinion; a second pinion attached to a portion of the second swing arm separated from a rotation axis of the second swing arm; a second rack attachable to the door (220R, 220L) and meshed with the second pinion; an arm connection shaft including a first arm shaft connected to the first swing arm and having an axis coinciding with the rotation axis of the first swing arm, a second arm shaft connected to the second swing arm and having an axis coinciding with the rotation axis of the second swing arm, and a third arm shaft connecting the first arm shaft and the second arm shaft, wherein the arm connection shaft rotates integrally with the first swing arm and the second swing arm to synchronize rotation of the first swing arm and rotation of the second swing arm; and a pinion connection shaft including a first pinion shaft connected to the first pinion and having an axis coinciding with a rotation axis of the first pinion, a second pinion shaft connected to the second pinion and having an axis coinciding with a rotation axis of the second pinion, and a third pinion shaft connecting the first pinion shaft and the second pinion shaft, wherein the pinion connection shaft rotates integrally with the first pinion and the second pinion to synchronize rotation of the first pinion and rotation of the second pinion, wherein the arm connection shaft includes a first universal joint, which connects the first arm shaft and the third arm shaft, and a second universal joint, which connects the second arm shaft and the third arm shaft, and the pinion connection shaft includes a third universal joint, which connects the first pinion shaft and the third pinion shaft, and a fourth universal joint, which connects the second pinion shaft and the third pinion shaft.