A terminal state measurement device for a coaxial cable includes: a conductive cylindrical body which comes close to a front end edge of an outer conductor terminal to bring a front end face of the conductive cylindrical body into contact with the front end edge when the outer conductor terminal is connected to a coaxial cable; a conduction measurement element displaceable with respect to the conductive cylindrical body in an axial direction, and which contacts a front end of an inner conductor terminal from the front side to displace in the axial direction in accordance with an insertion position of the inner conductor terminal; a displacement measurement device which measures a position of the front end of the inner conductor terminal; and an insulation determination unit which determines an insulation quality based on a conduction state of the conduction measurement element and the conductive cylindrical body.