A traction balance adjustment mechanism, comprising: a movable part configured to operate through at least one degree of freedom; power transmission members connected to the movable part; and a traction part configured to pull one of the power transmission members and push out the other; wherein a length of the one power transmission member pulled by the traction part is longer than a length of the other power transmission member pushed out, wherein the traction part includes a driving gear (64a 1, 64b 1) that is capable of rotating with respect to a given axis, and a first driven member (64a 2) and a second driven member (64b 2) in mesh with the driving gear (64a 1, 64b 1), the power transmission members include at least one pair of a first power transmission member and a second power transmission member, the movable part includes a first connector that makes a connection to one end of the first power transmission member and a second connector that makes a connection to one end of the second power transmission member, the first driven member (64a 2) includes a first mount (64a 4) to which the first power transmission member is attached, the second driven member (64b 2) includes a second mount (64b 4) to which the second power transmission member is attached, the driving gear (64a 1, 64b 1) comprises a first driving gear (64a 1) provided with a first driving smallest-diameter site (64a min1) and a first driving largest-diameter site (64a max) and a second driving gear (64b 1) provided with a second driving smallest-diameter site (64b min1) and a second driving largest-diameter site (64b max1), a tooth tilting rate of the first driven member (64a 2) is compatible with an incremental/decremental rate of diameter of the first driving gear (64a 1) such that a straight line in an extension direction of the first power transmission member lies always in the same position, and a tooth tilting rate of the second driven member (64b 2) is compatible with an incremental/ decremental rate of diameter of the second driving gear (64b 1) such that a straight line in an extension direction of the second power transmission member lies always in the same position. a movable part configured to operate through at least one degree of freedom; power transmission members connected to the movable part; and a traction part configured to pull one of the power transmission members and push out the other; wherein a length of the one power transmission member pulled by the traction part is longer than a length of the other power transmission member pushed out, wherein the traction part includes a driving gear (64a 1, 64b 1) that is capable of rotating with respect to a given axis, and a first driven member (64a 2) and a second driven member (64b 2) in mesh with the driving gear (64a 1, 64b 1), the power transmission members include at least one pair of a first power transmission member and a second power transmission member, the movable part includes a first connector that makes a connection to one end of the first power transmission member and a second connector that makes a connection to one end of the second power transmission member, the first driven member (64a 2) includes a first mount (64a 4) to which the first power transmission member is attached, the second driven member (64b 2) includes a second mount (64b 4) to which the second power transmission member is attached, the driving gear (64a 1, 64b 1) comprises a first driving gear (64a 1) provided with a first driving smallest-diameter site (64a min1) and a first driving largest-diameter site (64a max) and a second driving gear (64b 1) provided with a second driving smallest-diameter site (64b min1) and a second driving largest-diameter site (64b max1), a tooth tilting rate of the first driven member (64a 2) is compatible with an incremental/decremental rate of diameter of the first driving gear (64a 1) such that a straight line in an extension direction of the first power transmission member lies always in the same position, and a tooth tilting rate of the second driven member (64b 2) is compatible with an incremental/ decremental rate of diameter of the second driving gear (64b 1) such that a straight line in an extension direction of the second power transmission member lies always in the same position.