The dataset includes rock magnetic end-member unmixing data of sediment cores from Site C0023 (Hole A) that was recovered during International Ocean Discovery Program (IODP) Expedition 370 in the Nankai Trough offshore Japan in the Pacific Ocean (Drilling vessel Chikyu). Site C0023 was established on 17 September 2016. Coring terminated on 3 November 2016.End-member modelling of isothermal remanent magnetization (IRM) acquisition curves were performed to characterize the iron mineralogy. IRM acquisition curves were measured using a Princeton Measurements Corporation Vibrating Sample Magnetometer (VSM). IRM was imparted stepwise (non-linearly) up to a maximum field of 1 T with an averaging time of 200 ms. Unmixing of IRM acquisition curves were performed using the web application MAX UnMix by Maxbauer et al. (2016). Mean coervity (Bh) is given in log10 B mT and dispersion parameter (DP) in log. EC is the extrapolated contribution to the total IRM.