A hydraulic turbine for hydraulic power generation comprising: a turbine body including a runner configured to be rotated by water flowing therein during hydraulic turbine operation; a guide vane configured to be rotated to change an opening angle and to thereby adjust a flow rate of water flowing into the runner ; a stay vane configured to guide the water to the guide vane during hydraulic turbine operation; and upper and lower covers opposite to each other, wherein the guide vane is provided between the upper cover and the lower cover and the guide vane is rotatably supported by the upper and lower covers ; a running water surface provided in the turbine body , the running water surface defining a channel for water; characterised by a coating layer provided on the running water surface of the runner , of the guide vane , of the upper cover and of the lower cover , the coating layer being formed by hydrophilic paint in order to reduce the friction loss of the water flow flowing in the channel , wherein the running water surface provided for the upper cover and the running water surface provided for the lower cover each have a respective cover non-coating region in which the coating layer is not provided, and the cover non-coating region is formed to include a rotation region of the guide vane when viewed in a direction taken along a rotational axis of the guide vane . a turbine body including a runner configured to be rotated by water flowing therein during hydraulic turbine operation; a guide vane configured to be rotated to change an opening angle and to thereby adjust a flow rate of water flowing into the runner ; a stay vane configured to guide the water to the guide vane during hydraulic turbine operation; and upper and lower covers opposite to each other, wherein the guide vane is provided between the upper cover and the lower cover and the guide vane is rotatably supported by the upper and lower covers ; a runner configured to be rotated by water flowing therein during hydraulic turbine operation; a guide vane configured to be rotated to change an opening angle and to thereby adjust a flow rate of water flowing into the runner ; a stay vane configured to guide the water to the guide vane during hydraulic turbine operation; and upper and lower covers opposite to each other, wherein the guide vane is provided between the upper cover and the lower cover and the guide vane is rotatably supported by the upper and lower covers ; a running water surface provided in the turbine body , the running water surface defining a channel for water; characterised by a coating layer provided on the running water surface of the runner , of the guide vane , of the upper cover and of the lower cover , the coating layer being formed by hydrophilic paint in order to reduce the friction loss of the water flow flowing in the channel , wherein the running water surface provided for the upper cover and the running water surface provided for the lower cover each have a respective cover non-coating region in which the coating layer is not provided, and the cover non-coating region is formed to include a rotation region of the guide vane when viewed in a direction taken along a rotational axis of the guide vane . <EOS>