An imaging device reads an output level of a pixel circuit constituting a pixel array by supplying current to the pixel circuit. It reads a signal level and reset level from the pixel circuit by supplying it with the current from a current source circuit, and stores them into a line memory. A pixel level of the pixel circuit is obtained by a differential amplifier that outputs the difference between the signal level and reset level of the same pixel circuit. The gate potential of a current copier transistor that supplies the read current is set at a value that enables the read current to take a constant value from column to column of the pixel array. The image device can suppress variations in the current copier circuit provided for each array column of the pixel circuits, thereby reducing string-like noise in the image picked up.