A solid-state imaging apparatus comprising: a pixel unit including a plurality of pixels for photoelectric conversion arranged in a matrix; a ramp signal generator configured to generate a first time-changing ramp signal during a first analog-to-digital conversion period, and to generate a second time-changing ramp signal during a second analog-to-digital conversion period; a plurality of comparators each arranged correspondingly to each of columns of the matrix; and a plurality of memories each arranged correspondingly to each of columns of the matrix, wherein the comparators compare the first time-changing ramp signal with a signal according to a release of reset of the pixels during the first analog-to-digital conversion period, and compare the second time-changing ramp signal with a signal according to the photoelectric conversion of the pixels during the second analog-to-digital conversion period, the memories store, as a first digital data, a count value of counting from a start of changing the first time-changing ramp signal until an inversion of an output of the comparator, during the first analog-to-digital conversion period, the memories store, as a second digital data, a count value of counting from a start of changing the second time-changing ramp signal until the inversion of the output of the comparator, during the second analog-to-digital conversion period, the ramp signal generator includes a first capacitor element and a current generator configured to supply a current to the first capacitor element, the first capacitor element samples a bias voltage by being supplied with the current before the first and second analog-to-digital conversion periods (T2, T3), and holds the bias voltage, and the ramp signal generator generates the first time-changing ramp signal based on the bias voltage held by the first capacitor element, and the second time-changing ramp signal based on the bias voltage held by the first capacitor element and used for generating the first time-changing ramp signal. a pixel unit including a plurality of pixels for photoelectric conversion arranged in a matrix; a ramp signal generator configured to generate a first time-changing ramp signal during a first analog-to-digital conversion period, and to generate a second time-changing ramp signal during a second analog-to-digital conversion period; a plurality of comparators each arranged correspondingly to each of columns of the matrix; and a plurality of memories each arranged correspondingly to each of columns of the matrix, wherein the comparators compare the first time-changing ramp signal with a signal according to a release of reset of the pixels during the first analog-to-digital conversion period, and compare the second time-changing ramp signal with a signal according to the photoelectric conversion of the pixels during the second analog-to-digital conversion period, the memories store, as a first digital data, a count value of counting from a start of changing the first time-changing ramp signal until an inversion of an output of the comparator, during the first analog-to-digital conversion period, the memories store, as a second digital data, a count value of counting from a start of changing the second time-changing ramp signal until the inversion of the output of the comparator, during the second analog-to-digital conversion period, the ramp signal generator includes a first capacitor element and a current generator configured to supply a current to the first capacitor element, the first capacitor element samples a bias voltage by being supplied with the current before the first and second analog-to-digital conversion periods (T2, T3), and holds the bias voltage, and the ramp signal generator generates the first time-changing ramp signal based on the bias voltage held by the first capacitor element, and the second time-changing ramp signal based on the bias voltage held by the first capacitor element and used for generating the first time-changing ramp signal.