An optimal multitarget rendezvous problem for an active debris removal (ADR) mission using multiple chaser spacecraft is proposed. The problem is formulated mathematically as a variant of the vehicle routing problem with profits, which determines a set of rendezvous sequences and associated trajectories that maximize the sum of profits collected by conducting tasks under the constraints on the required Delta V and the duration of the mission. A two-phase framework is developed to solve the proposed multitarget rendezvous problem. The framework can reduce the complexity of the problem, by decomposing it into two different types of optimizations (trajectory optimization and combinatorial optimization), and obtain its solution efficiently. In the first phase of the framework, a series of trajectory optimization problems for all departure/arrival debris pairs is solved to generate the elementary solutions, a database of rendezvous trajectories. The second phase combines the elementary solutions prepared in the first phase to obtain the final solution of the problem. The column-generation technique is adopted to explore the routes (rendezvous sequences) that are relevant to the optimization problem. The validity of the proposed problem formulation and the optimization framework is demonstrated through ADR case studies.