Magnetic‐property measurements of pyrolytic carbon prepared by the thermal chemical vapor deposition of adamantane were carried out using the Faraday balance method and the electron‐spin‐resonance (ESR) spectroscopy. Two kinds of samples under different preparation batches were employed to examine the batch dependence as well as the magnetic properties of each. The content of ferromagnetic metallic oxide as impurity in these samples has been confirmed to be low enough not to influence the present magnetic‐property measurements. Analysis of the magnetization curves observed in the magnetic field range 0–5 T has shown that these samples are basically superparamagnetic and, even, ferromagnetic at low temperature in one sample. The ESR measurements have also supported these aspects. The connection of the magnetic properties and batch dependence obtained here will be discussed in detail.