An endoscope apparatus, comprising an endoscope; a control section to which the endoscope is electrically connected; and a connector system including: a plug section provided at a universal cord section of the endoscope, a land (43, 44) provided at the plug section and having conductivity, a receptacle section provided at the control section to receive a signal from the endoscope via the land (43, 44), and having a concave portion in an inside of which the plug section can be inserted, a ground contact point which is electrically connected to a ground potential and provided at the receptacle section, the ground contact point having conductivity, and an electric contact point which is different from the ground contact point and provided at the receptacle section, the electric contact point having conductivity, in which the plug section is inserted into or extracted from the receptacle section, whereby the land (43, 44), and the ground contact point and the electric contact point are caused to abut on each other or separate from each other, characterized in that the plug section includes a flange portion including a first inclined surface portion which increases in diameter toward an extraction direction, and a second inclined surface portion which decreases in diameter toward the extraction direction on an extraction direction side of the first inclined surface portion, in which an inclination angle with respect to an insertion direction of the second inclined surface portion is larger than an inclination angle with respect to the insertion direction of the first inclined surface portion, the receptacle section includes a ball which is projectable /retractable from a side surface portion of the concave portion, and provided to abut on the first inclined surface portion and the second inclined surface portion of the flange portion during the insertion of the plug section and an urging member which urges the ball in a direction to project into the concave portion from the side surface portion, the ground contact point abuts on and electrically connected with the land (43, 44) at a position where the ball of the receptacle section abuts on the first inclined surface portion, when the plug section is partially inserted into the receptacle section, and the plug section is further inserted into the receptacle section and thereby the electric contact point abuts on and electrically connected with the land (43, 44) at a position where the ball and the second inclined surface portion abut on each other, while the ground contact point continues to abut on the land (43, 44). a plug section provided at a universal cord section of the endoscope, a land (43, 44) provided at the plug section and having conductivity, a receptacle section provided at the control section to receive a signal from the endoscope via the land (43, 44), and having a concave portion in an inside of which the plug section can be inserted, a ground contact point which is electrically connected to a ground potential and provided at the receptacle section, the ground contact point having conductivity, and an electric contact point which is different from the ground contact point and provided at the receptacle section, the electric contact point having conductivity, in which the plug section is inserted into or extracted from the receptacle section, whereby the land (43, 44), and the ground contact point and the electric contact point are caused to abut on each other or separate from each other,