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Several approaches have been proposed to analyze the human operator's behavior in a manual control system. They mainly use the transfer function method or the state variable method; however, these are not sufficient in making the human control strategy clear because the human operator's behavior is intrinsically nonlinear and vague, although it shows excellent adaptability. The human operator's adaptability discussed here is defined as follows: "Adaptation is a process through which a well-trained operator, who knows how to react to a sudden change in the plant dynamics, abjusts his/her control strategy." Several attempts have been made to model the human operator's adaptability. However, it would be natural to explain human behavior by linguistic or fuzzy set theoretical expressions rather than by the transfer function or a state-variable expression. One of the authors has analyzed the human operator's behavior in manual control systems with some nonlinear controlled object with the aid of the fuzzy set theory. The authors have also proposed an adaptive fuzzy model of the human operator in response to a sudden change in plant dynamics, although the time delay of the operator is neglected in that model. In this study, we first suggest a method for identifying the human operator's time delay by examining the causal relation between the control deviation and the manipulating variable obtained from a man-machine control experiment. In the experiment, the operator is required to control the second-order servo mechanism and to take compensatory tracking action for the stationary random input. The feedback loop in the servo breaks suddenly, and consequently, the operator has to adapt his control action to the change in dynamics of the controlled object. The experimental results also show that the whole control process consists of three modes: (1) steady state control before the dynamics changes; (2) transient wild oscillatory control immediately after the change; and (3) steady state control after wards (2). Mode (2) is the adaptive process in which the operator's control action is a kind of damped bang-bang operation. Then the operator's fuzzy model, taking into account the time delay, is constructed. The model has a hierarchical structure with two sets of meta-rules and three sets of fuzzy rules. The validity of the model is verified by the simulation; the effect of the display gain on the manual control is also discussed.