A-kinase anchoring protein 12 (AKAP12) is a key scaffolding protein that regulates cellular signaling by anchoring protein kinase A (PKA) and other signaling molecules. While recent studies suggest an important role for AKAP12 in the brain, including cognitive functions, its role in middle-aged mice and potential sex differences are not fully understood. Therefore, this study investigated the effects of AKAP12 on cognitive and exploratory behavior in middle-aged mice, focusing on sex differences. Cognitive function was assessed using the spontaneous Y-maze test and the novel object recognition test (NORT). No significant sex differences in cognitive function were found in middle-aged C57BL/6J mice; however, female mice showed greater exploratory behavior during the NORT. In addition, both middle-aged male and female Akap12 knockout (KO) mice performed similarly to wild-type (WT) mice in the Y-maze test, but had lower discrimination indices in the NORT, suggesting a potential role for AKAP12 in short-term memory. Notably, exploratory behavior was suppressed in female Akap12 KO mice compared to WT mice, whereas male Akap12 KO mice did not show this effect. There were no significant differences in movement distance and velocity during the Y-maze test and NORT between WT and KO mice of either sex. These results indicate that AKAP12 affects cognitive function and exploratory behavior in middle-aged mice and that these effects differ between sexes.