A partial iterative detection and decoding apparatus in a Multiple Input Multiple Output (MIMO) system includes a detector for detecting signals received through at least one receive antenna to generate a first soft decision value, a decoder for decoding the first soft decision value to generate a second soft decision value, and a reliability determiner for determining a signal to be iteratively detected and decoded by using the second soft decision value. Accordingly, the complexity of the receiver is reduced and the number of iterations limited due to the complexity is increased, thereby improving the performance of the receiver.