A salinity gradient and solar energy hybrid power generation apparatus comprising: a solar photovoltaic power generation and/or solar thermal power generation unit, supplied with first freshwater as cooling water, which has a solar cell panel having a first surface having a light receiving portion and a second surface opposite to the first surface, and a salinity gradient power generation unit supplied with first saltwater and the first freshwater raised in temperature due to heat exchange with the solar cell panel to generate electricity by a salinity gradient between the first freshwater and the first saltwater, the salinity gradient power generation unit comprises: a housing having a first freshwater inflow port, a first freshwater outflow port, a first saltwater inflow port, and a first saltwater outflow port; an anode and a cathode disposed in the housing and spaced a predetermined distance from each other; and a plurality of ion exchange membranes arranged between the anode and the cathode to compart a first flow path through which the first freshwater flows and a second flow path through which the first saltwater flows, the housing has a first freshwater inflow portion configured to fluidly connect the first freshwater inflow port and the first flow path, and the first freshwater inflow portion is provided to achieve heat exchange between the second surface of the solar cell panel and the influent first freshwater, wherein the first freshwater inflow portion has at least one surface forming a space into which the first freshwater flows, the surface being the second surface of the solar cell panel, and wherein when the first freshwater flows into the first freshwater inflow portion, the first freshwater is brought into contact with the second surface of the solar cell panel. a solar photovoltaic power generation and/or solar thermal power generation unit, supplied with first freshwater as cooling water, which has a solar cell panel having a first surface having a light receiving portion and a second surface opposite to the first surface, and a salinity gradient power generation unit supplied with first saltwater and the first freshwater raised in temperature due to heat exchange with the solar cell panel to generate electricity by a salinity gradient between the first freshwater and the first saltwater, the salinity gradient power generation unit comprises: a housing having a first freshwater inflow port, a first freshwater outflow port, a first saltwater inflow port, and a first saltwater outflow port; an anode and a cathode disposed in the housing and spaced a predetermined distance from each other; and a plurality of ion exchange membranes arranged between the anode and the cathode to compart a first flow path through which the first freshwater flows and a second flow path through which the first saltwater flows, the housing has a first freshwater inflow portion configured to fluidly connect the first freshwater inflow port and the first flow path, and the first freshwater inflow portion is provided to achieve heat exchange between the second surface of the solar cell panel and the influent first freshwater, wherein the first freshwater inflow portion has at least one surface forming a space into which the first freshwater flows, the surface being the second surface of the solar cell panel, and wherein when the first freshwater flows into the first freshwater inflow portion, the first freshwater is brought into contact with the second surface of the solar cell panel. a housing having a first freshwater inflow port, a first freshwater outflow port, a first saltwater inflow port, and a first saltwater outflow port; an anode and a cathode disposed in the housing and spaced a predetermined distance from each other; and a plurality of ion exchange membranes arranged between the anode and the cathode to compart a first flow path through which the first freshwater flows and a second flow path through which the first saltwater flows, the housing has a first freshwater inflow portion configured to fluidly connect the first freshwater inflow port and the first flow path, and the first freshwater inflow portion is provided to achieve heat exchange between the second surface of the solar cell panel and the influent first freshwater, wherein the first freshwater inflow portion has at least one surface forming a space into which the first freshwater flows, the surface being the second surface of the solar cell panel, and wherein when the first freshwater flows into the first freshwater inflow portion, the first freshwater is brought into contact with the second surface of the solar cell panel.