A method for mounting a balancer to a robot, the robot comprising: a robot arm (12, 13, 14, 15); a balancer pressurized in advance by a predetermined amount of pressure and contracted to a dimension smaller than a predetermined mounting dimension of the robot arm (12, 13, 14, 15); and a first mounting portion and a second mounting portion disposed on the robot arm (12, 13, 14, 15) to respectively accept a first end and a second end of the balancer so that the first end and the second end of the balancer are mounted on the robot arm (12, 13, 14, 15), at least one mounting portion among the first mounting portion and the second mounting portion accepting the corresponding end, among the first end and the second end, of the balancer in a direction approximately parallel to a direction in which the balancer is expanded and contracted, the method comprising: mounting the second end of the balancer on the second mounting portion, wherein with the second end of the balancer mounted on the second mounting portion, a predetermined length of gap is defined between the first end of the balancer and the first mounting portion; and generating, by a connection mechanism comprised in at least one mounting portion among the first mounting portion and the second mounting portion, a connection force in the direction approximately parallel to the direction in which the balancer is expanded and contracted so as to fill the gap and thereby mount the first end of the balancer to the first mounting portion in the direction approximately parallel to the direction in which the balancer is expanded and contracted. a robot arm (12, 13, 14, 15); a balancer pressurized in advance by a predetermined amount of pressure and contracted to a dimension smaller than a predetermined mounting dimension of the robot arm (12, 13, 14, 15); and a first mounting portion and a second mounting portion disposed on the robot arm (12, 13, 14, 15) to respectively accept a first end and a second end of the balancer so that the first end and the second end of the balancer are mounted on the robot arm (12, 13, 14, 15), at least one mounting portion among the first mounting portion and the second mounting portion accepting the corresponding end, among the first end and the second end, of the balancer in a direction approximately parallel to a direction in which the balancer is expanded and contracted, the method comprising: mounting the second end of the balancer on the second mounting portion, wherein with the second end of the balancer mounted on the second mounting portion, a predetermined length of gap is defined between the first end of the balancer and the first mounting portion; and generating, by a connection mechanism comprised in at least one mounting portion among the first mounting portion and the second mounting portion, a connection force in the direction approximately parallel to the direction in which the balancer is expanded and contracted so as to fill the gap and thereby mount the first end of the balancer to the first mounting portion in the direction approximately parallel to the direction in which the balancer is expanded and contracted. mounting the second end of the balancer on the second mounting portion, wherein with the second end of the balancer mounted on the second mounting portion, a predetermined length of gap is defined between the first end of the balancer and the first mounting portion; and generating, by a connection mechanism comprised in at least one mounting portion among the first mounting portion and the second mounting portion, a connection force in the direction approximately parallel to the direction in which the balancer is expanded and contracted so as to fill the gap and thereby mount the first end of the balancer to the first mounting portion in the direction approximately parallel to the direction in which the balancer is expanded and contracted.