We investigated the I-V hysteresis of tin perovskite solar cells using capacitance-voltage (C-V) measurement coupled with charge modulation spectroscopy (CMS). The C-V characteristics and CMS of the solar cell device (ITO/PEDOT:PSS/CH3NH3SnI3 (MASnI(3))/C-60/Al) showed that electrons inject from a C-60 layer into an MASnI(3) layer at positive bias voltage, while the injected electrons return to a C-60 layer at negative bias voltage. Results suggested that I-V hysteresis of tin perovskite solar cells is originated from the carrier injection into an MASnI(3) layer. This study provides a method for evaluating the carrier motion in tin perovskite solar cells.