A propulsive force generating device includes a parent body of rotation rotatably arranged, means for rotationally driving the parent body of rotation at a rotational angular velocity ω0, n (n≥1 integer) child bodies of rotation arranged on the body of rotation and having rotating axes in the circumferential direction of the parent body of rotation, and means for rotationally driving the child bodies of rotation at a rotational angular velocity ω1 by flexible binding. The rotational angular velocity ω0 and the rotational angular velocity ω1 have the same sign and satisfy the following numerical expression:







2
⁢

π
2


n

⁢

ω
0


≤

ω
1