An image sensing apparatus (100, 300, 600, 800, 900, 1000) comprising: first and second pixels (A11, B11) each including a photoelectric conversion unit; a column signal line (RL1-RL4) connected to the first and second pixels; an output line (121, 122) having a capacitance; a readout circuit (110, 310, 610, 810, 910, 1010) configured to read out signals from the first and second pixels via the column signal line to supply signals associated with the first and second pixels to the output line; and an output unit (120, 1220) configured to output signals in accordance with the signals supplied to the output line from the readout circuit, wherein the readout circuit includes a first accumulation unit (203, 1103) configured to accumulate electric charges corresponding to the signal read out to the column signal line, a first opening/closing unit (210, 1110) configured to open/close connection between the column signal line and the first accumulation unit, a second accumulation unit, a transmission unit (204, 504, 1104, 1304, 1404) including a buffer amplifier which is an impedance converter configured to supply a signal corresponding to the electric charges held by the first accumulation unit to the second accumulation unit, and a second opening/closing unit (205, 1105) configured to open/close connection between the transmission unit and the second accumulation unit, wherein the signal held by the second accumulation unit is read out to the output unit according to capacitive division between the capacitance of the second accumulation unit and the capacitance of the output line, wherein the apparatus is characterized in that the capacitance of the first accumulation unit is smaller than the capacitance of the second accumulation unit, the transmission unit (204, 504, 1104, 1304, 1404) is configured to supply, during a first period, a signal which is associated with the first pixel and which corresponds to the electric charges held by the first accumulation unit to the second accumulation unit, and the first accumulation unit (203, 1103) is configured to perform, during a second period after the first period, an operation in which electric charges corresponding to the signal read out from the second pixel via the column signal line through the first opening/closing unit are accumulated, wherein the second period is a period in which an operation of transmitting the signal associated with the first pixel from the second accumulation unit to the output unit (120, 1220) is performed. first and second pixels (A11, B11) each including a photoelectric conversion unit; a column signal line (RL1-RL4) connected to the first and second pixels; an output line (121, 122) having a capacitance; a readout circuit (110, 310, 610, 810, 910, 1010) configured to read out signals from the first and second pixels via the column signal line to supply signals associated with the first and second pixels to the output line; and an output unit (120, 1220) configured to output signals in accordance with the signals supplied to the output line from the readout circuit, wherein the readout circuit includes a first accumulation unit (203, 1103) configured to accumulate electric charges corresponding to the signal read out to the column signal line, a first opening/closing unit (210, 1110) configured to open/close connection between the column signal line and the first accumulation unit, a second accumulation unit, a transmission unit (204, 504, 1104, 1304, 1404) including a buffer amplifier which is an impedance converter configured to supply a signal corresponding to the electric charges held by the first accumulation unit to the second accumulation unit, and a second opening/closing unit (205, 1105) configured to open/close connection between the transmission unit and the second accumulation unit, wherein the signal held by the second accumulation unit is read out to the output unit according to capacitive division between the capacitance of the second accumulation unit and the capacitance of the output line, wherein the apparatus is characterized in that the capacitance of the first accumulation unit is smaller than the capacitance of the second accumulation unit, the transmission unit (204, 504, 1104, 1304, 1404) is configured to supply, during a first period, a signal which is associated with the first pixel and which corresponds to the electric charges held by the first accumulation unit to the second accumulation unit, and the first accumulation unit (203, 1103) is configured to perform, during a second period after the first period, an operation in which electric charges corresponding to the signal read out from the second pixel via the column signal line through the first opening/closing unit are accumulated, wherein the second period is a period in which an operation of transmitting the signal associated with the first pixel from the second accumulation unit to the output unit (120, 1220) is performed.