The diagnosis of child maltreatment leading to head injury is challenging. Here, we present the case of a 3-month-old female infant who presented with focal seizures that lasted for several minutes. After admission, she began to show intermittent clusters of head nods, irritable crying, arching, writhing, stiffening, and jerking of both arms. These results and electroencephalography findings were attributed as the diagnosis of infantile spasms (IS). Brain computed tomography and magnetic resonance imaging (MRI) revealed the presence of chronic subdural hematoma mixed with acute ischemic injuries. Examination of the eye fundus confirmed the presence of retinal hemorrhage. Therefore, all evidence pointed to a diagnosis of shaken baby syndrome (SBS). Based on this case, we suggest that physicians should consider a diagnosis of SBS for children with new-onset IS and that should be evaluated, diagnosed, and treated as promptly as possible.