A printing apparatus configured to perform printing on a sheet-like recording medium into which liquid can penetrate, the printing apparatus comprising: a discharge unit configured to discharge, onto one side of the recording medium, ink and penetration liquid which promotes penetration of the ink into the other side of the recording medium; and a movement unit configured to move the discharge unit and the recording medium relative to each other when the printing is performed, wherein the recording medium has an elongated shape, and the movement unit includes a transport unit configured to transport the recording medium in a longitudinal direction of the recording medium and a reciprocating movement unit configured to reciprocate the discharge unit in a direction crossing the direction in which the recording medium is transported, characterized in that: the printing apparatus further comprises: an adjustment unit configured to adjust a discharge amount of the penetration liquid discharged from the discharge unit onto the recording medium on the basis of at least a relative movement speed of the discharge unit to the recording medium, and a storage unit configured to store a first calibration curve representing a relationship between the transport speed and a difference in density between one side and the other side of the recording medium on which the printing has been performed and a second calibration curve representing a relationship of a mixing ratio of the ink and the penetration liquid when the printing was performed and the difference in density, wherein the adjustment unit is configured to adjust the discharge amount of the penetration liquid on the basis of a transport speed at which the recording medium is transported, and wherein the adjustment unit is configured to adjust the discharge amount of the penetration liquid by using the first calibration curve and the second calibration curve. a discharge unit configured to discharge, onto one side of the recording medium, ink and penetration liquid which promotes penetration of the ink into the other side of the recording medium; and a movement unit configured to move the discharge unit and the recording medium relative to each other when the printing is performed, wherein the recording medium has an elongated shape, and the movement unit includes a transport unit configured to transport the recording medium in a longitudinal direction of the recording medium and a reciprocating movement unit configured to reciprocate the discharge unit in a direction crossing the direction in which the recording medium is transported, characterized in that: a transport unit configured to transport the recording medium in a longitudinal direction of the recording medium and a reciprocating movement unit configured to reciprocate the discharge unit in a direction crossing the direction in which the recording medium is transported, characterized in that: the printing apparatus further comprises: an adjustment unit configured to adjust a discharge amount of the penetration liquid discharged from the discharge unit onto the recording medium on the basis of at least a relative movement speed of the discharge unit to the recording medium, and a storage unit configured to store a first calibration curve representing a relationship between the transport speed and a difference in density between one side and the other side of the recording medium on which the printing has been performed and a second calibration curve representing a relationship of a mixing ratio of the ink and the penetration liquid when the printing was performed and the difference in density, wherein an adjustment unit configured to adjust a discharge amount of the penetration liquid discharged from the discharge unit onto the recording medium on the basis of at least a relative movement speed of the discharge unit to the recording medium, and a storage unit configured to store a first calibration curve representing a relationship between the transport speed and a difference in density between one side and the other side of the recording medium on which the printing has been performed and a second calibration curve representing a relationship of a mixing ratio of the ink and the penetration liquid when the printing was performed and the difference in density, wherein a first calibration curve representing a relationship between the transport speed and a difference in density between one side and the other side of the recording medium on which the printing has been performed and a second calibration curve representing a relationship of a mixing ratio of the ink and the penetration liquid when the printing was performed and the difference in density, wherein the adjustment unit is configured to adjust the discharge amount of the penetration liquid on the basis of a transport speed at which the recording medium is transported, and wherein the adjustment unit is configured to adjust the discharge amount of the penetration liquid by using the first calibration curve and the second calibration curve.