A solid-state imaging device 2A includes a CCD-type solid-state imaging element 10 having an imaging plane 12 formed of M×N pixels that are two-dimensionally arrayed in M rows and N columns and N signal readout circuits 20 arranged on one end side in the column direction for each of the columns with respect to the plane 12 and for outputting electrical signals according to the magnitudes of charges taken out of the respective columns, respectively, a C-MOS-type semiconductor element 50 for digital-converting and sequentially outputting as serial signals electrical signals output from the circuits 20 for each of the columns, a heat transfer member 80 having a main surface 81a and a back surface 81b, and a cooling block 84 provided on the surface 81b, and the semiconductor element 50 and the surface 81a of the heat transfer member 80 are bonded to each other.