Mobile radiography in a neonatal intensive care unit (NICU) is expected to show a more complex distribution of scattered X-rays because the child patient is exposed to X-rays through an incubator cover. To discuss appropriate protective measures, it is necessary to identify each source of the scattered X-rays; however, this is difficult using only dose measurements. The study purpose was to use a self-made lead pinhole camera in a phantom study to visualize the scattered X-ray sources during portable radiography in an NICU with the goal of contributing to the optimization of occupational exposure management. The patient phantom was irradiated with primary X-rays and a pinhole image was obtained from scattered X-rays at the medical staff position. We observed that non-negligible scattered X-rays were generated not only from the patient phantom but also from the incubator cover and the dose-area product meter attached to the exit part of the X-ray equipment. The dose measurements also revealed that scattered X-ray doses were higher at the level of the incubator surface. Thus, for optimization of protection, it is desirable to take precautions such as preventing medical staff from approaching the aforementioned high-exposure positions and attaching protective curtains to the collimator cover of the X-ray tube.