A ramp signal generator and an image sensor including the same are disclosed, which relate to technology for allowing a ramp signal generator to reduce voltage drop and current deviation affected by fabrication change. The ramp signal generator includes a ramp array including a plurality of ramp circuits arranged in row and column directions and selectively activated by ramp control signals, and configured to generate an output current by summing currents from selectively activated ramp circuits, and a current-to-voltage converter configured to convert the output current into a voltage value to output the voltage value as a ramp signal. Each of the ramp circuits initializes a voltage of a charge node in response to an initialization voltage, and generates the output current based on charges in a charge transistor charged through the charge node when receiving a drive voltage.