A rail/canister type missile launcher, from which missiles are launched inside canisters, is acted by intermittent contact force occurred by the interaction between the missiles and canisters as well as the impact force occurred by the breakdown of the tension pin. These forces may give rise to harmful effects on the accuracy of the missile performances, This paper deals with the vibration responses of significant parts in rail/canister type missile launcher by using a structural dynamic analysis and predicts an initial state of the missile involved in a contact problem between the missile and its canister. In this dynamic analysis, a simplified finite element model was used and its validity was verified by comparing the modal properties with the experimental results. And the contact phenomena occurring between the missile and canister are analyzed by applying the nonlinear contact force theory.