An image sensor comprising: a pixel array in which a plurality of pixels are arranged; and a row driver configured to transmit control signals to the pixel array, wherein the plurality of pixels each include a first photodiode (PD;PD1), a first transfer transistor configured to transfer photocharges generated by the first photodiode to a floating diffusion node, a conversion gain control transistor connected to the floating diffusion node and configured to adjust a gain with which the photocharges are converted into a voltage of the floating diffusion node, a first source follower configured to amplify the voltage of the floating diffusion node and output the amplified voltage to a first node, a precharge selection transistor having one end connected to the first node and another end connected to a second node, a first capacitor configured to sample a reset voltage corresponding to a voltage level of the floating diffusion node that is reset, a first sampling transistor having one end connected to the second node and another end connected to the first capacitor, a second capacitor configured to sample a first image voltage corresponding to the voltage level of the floating diffusion node according to the photocharges generated by the first photodiode, a second sampling transistor having one end connected to the second node and another end connected to the second capacitor, a second source follower configured to amplify a voltage of the second node and output the amplified voltage, and a first selection transistor connected between an output terminal of the second source follower and a column line, and characterized by a second selection transistor connected between the first node and the column line. a pixel array in which a plurality of pixels are arranged; and a row driver configured to transmit control signals to the pixel array, wherein the plurality of pixels each include a first photodiode (PD;PD1), a first transfer transistor configured to transfer photocharges generated by the first photodiode to a floating diffusion node, a conversion gain control transistor connected to the floating diffusion node and configured to adjust a gain with which the photocharges are converted into a voltage of the floating diffusion node, a first source follower configured to amplify the voltage of the floating diffusion node and output the amplified voltage to a first node, a precharge selection transistor having one end connected to the first node and another end connected to a second node, a first capacitor configured to sample a reset voltage corresponding to a voltage level of the floating diffusion node that is reset, a first sampling transistor having one end connected to the second node and another end connected to the first capacitor, a second capacitor configured to sample a first image voltage corresponding to the voltage level of the floating diffusion node according to the photocharges generated by the first photodiode, a second sampling transistor having one end connected to the second node and another end connected to the second capacitor, a second source follower configured to amplify a voltage of the second node and output the amplified voltage, and a first selection transistor connected between an output terminal of the second source follower and a column line, and characterized by a second selection transistor connected between the first node and the column line. a first photodiode (PD;PD1), a first transfer transistor configured to transfer photocharges generated by the first photodiode to a floating diffusion node, a conversion gain control transistor connected to the floating diffusion node and configured to adjust a gain with which the photocharges are converted into a voltage of the floating diffusion node, a first source follower configured to amplify the voltage of the floating diffusion node and output the amplified voltage to a first node, a precharge selection transistor having one end connected to the first node and another end connected to a second node, a first capacitor configured to sample a reset voltage corresponding to a voltage level of the floating diffusion node that is reset, a first sampling transistor having one end connected to the second node and another end connected to the first capacitor, a second capacitor configured to sample a first image voltage corresponding to the voltage level of the floating diffusion node according to the photocharges generated by the first photodiode, a second sampling transistor having one end connected to the second node and another end connected to the second capacitor, a second source follower configured to amplify a voltage of the second node and output the amplified voltage, and a first selection transistor connected between an output terminal of the second source follower and a column line, and characterized by a second selection transistor connected between the first node and the column line.