A wire harness installation structure comprising: a wire harness having bend flexibility; a protector configured to protect the wire harness while allowing the wire harness to make a bending movement about a bending position of the wire harness , the bending position being located between both ends of the wire harness ; and a bending motion mechanism that causes the wire harness to make the bending movement, wherein: the wire harness has a first portion (PT1) that is fixed to the protector , a second portion (PT2) that is distant from both of the first portion (PT1) and the protector beyond the bending position, and a third portion (PT3) that is located between the first portion (PT1) and the second portion (PT2), and the third portion (PT3) is offset in a direction of the bending movement from an imaginary straight line connecting the first portion (PT1) and the second portion (PT2); and the second portion (PT2) of the wire harness is fixed on a movable member of the bending motion mechanism ; characterized in that: the third portion (PT3) of the wire harness is fixed on a movable member of the bending motion mechanism and the wire harness is routed so that a second excess length between the second portion (PT2) and the third portion (PT3) is shorter than a first excess length between the first portion (PT1) and the third portion (PT3). a wire harness having bend flexibility; a protector configured to protect the wire harness while allowing the wire harness to make a bending movement about a bending position of the wire harness , the bending position being located between both ends of the wire harness ; and a bending motion mechanism that causes the wire harness to make the bending movement, wherein: the wire harness has a first portion (PT1) that is fixed to the protector , a second portion (PT2) that is distant from both of the first portion (PT1) and the protector beyond the bending position, and a third portion (PT3) that is located between the first portion (PT1) and the second portion (PT2), and the third portion (PT3) is offset in a direction of the bending movement from an imaginary straight line connecting the first portion (PT1) and the second portion (PT2); and the second portion (PT2) of the wire harness is fixed on a movable member of the bending motion mechanism ; characterized in that: the third portion (PT3) of the wire harness is fixed on a movable member of the bending motion mechanism and the wire harness is routed so that a second excess length between the second portion (PT2) and the third portion (PT3) is shorter than a first excess length between the first portion (PT1) and the third portion (PT3). the wire harness has a first portion (PT1) that is fixed to the protector , a second portion (PT2) that is distant from both of the first portion (PT1) and the protector beyond the bending position, and a third portion (PT3) that is located between the first portion (PT1) and the second portion (PT2), and the third portion (PT3) is offset in a direction of the bending movement from an imaginary straight line connecting the first portion (PT1) and the second portion (PT2); and the second portion (PT2) of the wire harness is fixed on a movable member of the bending motion mechanism ; characterized in that: the third portion (PT3) of the wire harness is fixed on a movable member of the bending motion mechanism and the wire harness is routed so that a second excess length between the second portion (PT2) and the third portion (PT3) is shorter than a first excess length between the first portion (PT1) and the third portion (PT3). the third portion (PT3) of the wire harness is fixed on a movable member of the bending motion mechanism and the wire harness is routed so that a second excess length between the second portion (PT2) and the third portion (PT3) is shorter than a first excess length between the first portion (PT1) and the third portion (PT3). <EOS>