A fast imaging device 32 has a charge signal converter 33, a charge signal accumulator 36 and a charge signal transporter 37. A charge signal accumulator 36 is provided to each charge signal converter 33. A charge signal accumulator 36 extends linearly while inclining with respect to a line L2 connecting charge signal converter 33. The other end of a charge signal accumulator 36, connected at one end thereof to a charge signal converter 33 constituting a corresponding column, merges to a charge signal transporter 37. This construction reduces noise and increases a frame rate.