Inferior temporal (IT) cortex in monkeys locates at the final stage of visual object processing. Although neuronal responses in this cortical region have been characterized with various task paradigms, it remains largely unknown how individual neurons interact to form functional circuits for implementing cognitive demands. Here, I will discuss microcircuit operations in macaque IT cortex in an object-association memory task, focusing on two different topics. The first topic is the circuit operation for object memory retrieval. We found the directed signal flow between functionally different classes of memory neurons that generates memory retrieval signal of visual objects. The second topic is hierarchical object processing across cortical areas. The representation of a given feature of visual objects has been believed to be constructed in the cortical area where that representation is prevalent. However, another possible scheme is that preparatory codes of a given feature are created in a lower-order area before their increase to become predominant in a higher-order area. In the object association task paradigm, we found the microcircuits that generate and increase the representations of object associations in successive lower- and higher-order areas in the IT cortex, respectively, consistent with the latter hypothesis. Together, these results demonstrate that examinations of microcircuit operations in monkeys performing an object association memory task provided the principles of cortical computations for representation and memory retrieval of visual objects.