A swinging joint device includes: a driving shaft member； a first swinging arm that is swingably supported about the driving shaft member； a driven shaft member that is arranged parallel to the driving shaft member； an interlocking swinging member that swings about the driven shaft member in an interlocking manner with swinging of the first swinging arm； an elastic body that is connected to the interlocking swinging member to generate an urging force in a direction opposite to an interlocking swinging direction of the interlocking swinging member； a rigidity variable portion that varies rigidity of the elastic body seen from the interlocking swinging member； a first angle detection portion that detects a swinging angle； and a control portion that controls the rigidity variable portion according to the swinging angle detected by the first angle detection portion to adjust the rigidity of the elastic body seen from the interlocking swinging member.
