An apparatus for membrane distillation using a solar absorber , comprising: a raw water circulation pipe to circulate raw water in a raw water tank; a solar heat absorbing device provided on one side of the raw water circulation pipe to heat the raw water in the raw water circulation pipe ; a raw water tank to receive the raw water heated by the solar heat absorbing device through the raw water circulation pipe and to supply the raw water to a membrane distillation module ; the membrane distillation module to produce treated water from the raw water through a membrane distillation process; and a coolant tank to supply a coolant to the membrane distillation module and to collect the treated water produced by the membrane distillation module , wherein a phase change material is provided on one side of the raw water tank , and the phase change material is adapted to absorb heat of the raw water and is adapted to store the heat when a temperature of the raw water is equal to or higher than a melting point of the phase change material of between 20°C and 60°C, and is adapted to release the stored heat when the temperature of the raw water is lower than the melting point of the phase change material , wherein an inner wall is provided at a location spaced from an inner surface of the raw water tank , and the phase change material is provided in a space between the inner surface and the inner wall , the phase change material provided between the inner surface and the inner wall surrounds the raw water of the raw water tank , and the space between the inner surface and the inner wall is spatially separated from a space in which the raw water of the raw water tank is provided. a raw water circulation pipe to circulate raw water in a raw water tank; a solar heat absorbing device provided on one side of the raw water circulation pipe to heat the raw water in the raw water circulation pipe ; a raw water tank to receive the raw water heated by the solar heat absorbing device through the raw water circulation pipe and to supply the raw water to a membrane distillation module ; the membrane distillation module to produce treated water from the raw water through a membrane distillation process; and a coolant tank to supply a coolant to the membrane distillation module and to collect the treated water produced by the membrane distillation module , wherein a phase change material is provided on one side of the raw water tank , and the phase change material is adapted to absorb heat of the raw water and is adapted to store the heat when a temperature of the raw water is equal to or higher than a melting point of the phase change material of between 20°C and 60°C, and is adapted to release the stored heat when the temperature of the raw water is lower than the melting point of the phase change material , wherein an inner wall is provided at a location spaced from an inner surface of the raw water tank , and the phase change material is provided in a space between the inner surface and the inner wall , the phase change material provided between the inner surface and the inner wall surrounds the raw water of the raw water tank , and the space between the inner surface and the inner wall is spatially separated from a space in which the raw water of the raw water tank is provided. <EOS>