A solid-state imaging device (1, 101) comprising; photoelectric converting sections (11, 12) provided so as to extend along a first direction and configured to generate an electric charge in response to incidence of light; transfer sections (21, 22, 121, 122) configured to transfer the electric charge generated in the photoelectric converting sections (11, 12), in the first direction or in a second direction opposite to the first direction and in response to three-phase or four-phase drive signals, wherein all the transfer sections (21, 22) of the solid state imaging device are configured to transfer the electric charges at a same time (t1, t2, t3, t4, t5, t6) into the same first or second direction; first buffer sections (31, 32) disposed adjacent to the photoelectric converting sections (11, 12) in the first direction and configured to acquire the electric charge transferred in the first direction from the photoelectric converting sections (11, 12) by the transfer sections (21, 22, 121, 122) and transfer the acquired electric charge in the first direction in response to two-phase drive signals, wherein a semiconductor substrate of the first buffer sections (31, 32) has a variable impurity concentration in the first direction such that the first buffer sections (31, 32) have a stepped potential distribution in which potentials become deeper in the first direction; second buffer sections (51, 52) disposed adjacent to the photoelectric converting sections (11, 12) in the second direction and configured to acquire the electric charge transferred in the second direction from the photoelectric converting sections (11, 12) by the transfer sections (21, 22, 121, 122) and transfer the acquired electric charge in the second direction in response to two-phase drive signals, wherein a semiconductor substrate of the second buffer sections (51, 52) has a variable impurity concentration in the second direction such that the second buffer sections (51, 52) have a stepped potential distribution in which potentials become deeper in the second direction; first output sections disposed adjacent to the first buffer sections (31, 32) in the first direction and configured to acquire the electric charge transferred from the first buffer sections (31, 32) and output a signal according to the acquired electric charge; second output sections disposed adjacent to the second buffer sections (51, 52) in the second direction and configured to acquire the electric charge transferred from the second buffer sections (51, 52) and output a signal according to the acquired electric charge; the first buffer sections (31, 32) transfer the acquired electric charge to the first output section in the first direction; and the second buffer sections (51, 52) transfer the acquired electric charge to the second output section in the second direction, wherein the first buffer sections (31, 32) have a plurality of transfer electrodes (23A-23C, 33A-33D, 53A-53D, 123A-123D) disposed in juxtaposition in the first direction and configured to transfer the acquired electric charge when given respective corresponding drive signals out of the two-phase drive signals, and wherein the second buffer sections (51, 52) have a plurality of transfer electrodes (23A-23C, 33A-33D, 53A-53D, 123A-123D) disposed in juxtaposition in the second direction and configured to transfer the acquired electric charge when given respective corresponding drive signals out of the two-phase drive signals.