PROBLEM TO BE SOLVED: To provide an endoscope system capable of improving the color separability and the visibility of superficial blood vessels in narrowband light observation and also to provide an operating method of the endoscope system.SOLUTION: A light source device simultaneously produces violet narrowband light and green narrowband light. A primary color type imaging device of a primary color type endoscope outputs an R pixel signal, a G pixel signal, and a B pixel signal. In a primary color second processor 44, a matrix operation unit performs a matrix operation of the R, G, and B pixel signals, and produces first and second display signals D1 and D2. A mixed color corrector corrects the first and second display signals D1 and D2 on the basis of relational expressions of "D1=D1-K×D2" and "D2=D2-K×D1," where Krepresents the ratio of a signal value of the second display signal to a signal value of the first display signal under independent application of only the violet narrowband light, and Krepresents the ratio of a signal value of the first display signal to a signal value of the second display signal under independent application of only the green narrowband light.SELECTED DRAWING: Figure 13
