A muscular strength assisting apparatus may include: a wearing unit configured to enclose a part of a user's body; a tightening unit configured to pull the wearing unit in one or both directions; and/or a control unit configured to drive the tightening unit to tighten the part of the user's body on which the wearing unit is located, when it is determined that muscular contraction occurs at the part of the user's body on which the wearing unit is located. A method of controlling a muscular strength assisting apparatus may include: determining whether muscular contraction occurs at a part of a user's body that is enclosed by a wearing unit; and/or driving a tightening unit pulling the wearing unit in one direction or both directions to tighten the part of the user's body on which the wearing unit is located when it is determined that the muscular contraction occurs.