Resting-state study is a useful tool to investigate the brain activity related to cognitive abilities in children because it may be difficult for children to perform some experimental tasks. In the present study, we report a preliminary examination to associate the resting-state neuromagnetic signals from magnetoencephalogram (MEG) with cognitive abilities in children. We applied a non-linear time-series analysis for 90-s resting-state neuromagnetic signals and estimated interdependency of two channels of MEG signals. Then we examined the relation between the magnitudes of interdependency and the cognitive abilities and ages. Although we found some indications of age differences in the lateralization of interdependency, the results highlighted several limiting factors in measuring cognitive abilities and resting-state neuromegnetic signals in children and suggested that further elaboration of devices, procedures, and analysis would be warranted.