An operation appropriateness determination system for determining an operation appropriateness of an operator, the operation appropriateness indicating a degree of mental state in which an operator can perform an operation without errors, the system comprising: an authentication apparatus configured to identify an operator on a basis of a feature of the operator and to output information for identifying the operator; a biometric sensing apparatus configured to obtain biological information regarding the operator and to output the biological information; a storage device; and a signal processing apparatus, wherein the system further comprises an operation sensing apparatus configured to detect a load of an operation that is being performed by the operator and to output operation information indicating the detected load of the operation, wherein the load of the operation includes at least one selected from the group consisting of a driving condition of the operator who is a driver of a vehicle, the driving condition being obtained from temporal changes in a driving operation, such as acceleration, braking, and steering, an input condition of the operator who is engaged in an input operation with a computer, the input condition being obtained by monitoring a type of application used and inputs provided by the operator to an input device such as a keyboard and a mouse connected with the computer, and a problem solving condition of the operator who is a learner answering problems presented by a learning software, the problem solving condition being data regarding time taken until the learner solves a problem after a problem is presented, the difficulty of problems, or whether the learner has correctly solved a problem; and wherein the signal processing apparatus is configured to accumulate, while the operator is performing the operation, the information for identifying the operator, the biological information, the operation information, and time information in the storage device while associating the information for identifying the operator, the biological information, the operation information, and the time information with one another, estimate the biological information regarding the operator at a present time on a basis of a correlation between temporal changes in the operation information and temporal changes in the biological information in past accumulated in the storage device, and determine appropriateness of the operator for the operation by comparing the estimated biological information regarding the operator at the present time and the biological information regarding the operator at the present time obtained by the biometric sensing apparatus with each other. an authentication apparatus configured to identify an operator on a basis of a feature of the operator and to output information for identifying the operator; a biometric sensing apparatus configured to obtain biological information regarding the operator and to output the biological information; a storage device; and a signal processing apparatus, wherein the system further comprises an operation sensing apparatus configured to detect a load of an operation that is being performed by the operator and to output operation information indicating the detected load of the operation, wherein the load of the operation includes at least one selected from the group consisting of a driving condition of the operator who is a driver of a vehicle, the driving condition being obtained from temporal changes in a driving operation, such as acceleration, braking, and steering, an input condition of the operator who is engaged in an input operation with a computer, the input condition being obtained by monitoring a type of application used and inputs provided by the operator to an input device such as a keyboard and a mouse connected with the computer, and a problem solving condition of the operator who is a learner answering problems presented by a learning software, the problem solving condition being data regarding time taken until the learner solves a problem after a problem is presented, the difficulty of problems, or whether the learner has correctly solved a problem; and wherein the signal processing apparatus is configured to accumulate, while the operator is performing the operation, the information for identifying the operator, the biological information, the operation information, and time information in the storage device while associating the information for identifying the operator, the biological information, the operation information, and the time information with one another, estimate the biological information regarding the operator at a present time on a basis of a correlation between temporal changes in the operation information and temporal changes in the biological information in past accumulated in the storage device, and determine appropriateness of the operator for the operation by comparing the estimated biological information regarding the operator at the present time and the biological information regarding the operator at the present time obtained by the biometric sensing apparatus with each other.