This dissertation addresses the energy-efficient motion planning problem of attitude-fixed space manipulators with iterative optimization methods. Three specific subproblems are defined and efficient formulations and algorithms are suggested for the subproblems. The cost function to be minimized is defined as energy consumed in DC motors of manipulator joints and reaction wheels. The rotational disturbance caused by manipulator motion is assumed to be precisely compensated by reaction wheels so that the base attitude is fixed. For all subproblems, the limits of motor voltage and current are given as constraints. Other constraints are given for each problem as follows. For the Problem 1, manipulator joint path and deadline are given as constraints. For the Problem 2, manipulator end-effector trajectory and joint angle limits are given. Lastly, for the Problem 3, manipulator joint configurations at initial and final time and joint angle limits are given. To address the Problem 1 (the path-following problem), it is suggested to convert the original problem to a second order cone programming (SOCP) form, which is a special class of convex optimization problems. To address the Problem 2 (the end-effector trajectory specified problem), it is suggested to formulate a nonlinear constrained minimization problem with B-spline parameterization in the null space of end-effector motion. Also it is suggested to place the breakpoints of B-splines with consideration of the magnitude of end-effector acceleration. For the Problem 3 (the initial and final joint configuration specified problem), a three-phase iterative optimization algorithm is suggested. To speed up the overall optimization process, an efficient derivative computation algorithm is also suggested to evaluate the gradient of cost and the Jacobian of constraints. The effectiveness of the suggested methods is verified by various numerical experiments.