A state-of-attention determination apparatus comprising: an electroencephalogram measurement section for measuring an electroencephalogram signal of an operator; an oculomotor measurement section for measuring an oculomotor signal indicating an oculomotor movement of the operator; a standby state detection section for detecting a time period during which the operator is making preparations prior to beginning a driving operation; a determination criterion adjustment section for adjusting a determination criterion for determining a state of attention while the operator is performing a driving operation, the determination criterion adjustment section is configured to calculate an eye fixation related potential of the electroencephalogram signal measured at least in the time period by using the oculomotor signal, and configured to adjust the determination criterion based on the calculated eye fixation related potential; a state-of-attention determination section for calculating an eye fixation related potential from the electroencephalogram signal and the oculomotor signal measured after the operator begins a driving operation, and wherein the state-of-attention determination section is configured to determine a state of attention of the operator performing the driving operation based on the calculated eye fixation related potential and the adjusted determination criterion; and an output section for acting to call attention of the operator based on a result of determination, wherein the state-of-attention determination section is configured to determine the state of attention of the operator by comparing an amplitude value of a lambda response of the arithmetic-meaned eye fixation related potential against a determination threshold which is the determination criterion. an electroencephalogram measurement section for measuring an electroencephalogram signal of an operator; an oculomotor measurement section for measuring an oculomotor signal indicating an oculomotor movement of the operator; a standby state detection section for detecting a time period during which the operator is making preparations prior to beginning a driving operation; a determination criterion adjustment section for adjusting a determination criterion for determining a state of attention while the operator is performing a driving operation, the determination criterion adjustment section is configured to calculate an eye fixation related potential of the electroencephalogram signal measured at least in the time period by using the oculomotor signal, and configured to adjust the determination criterion based on the calculated eye fixation related potential; a state-of-attention determination section for calculating an eye fixation related potential from the electroencephalogram signal and the oculomotor signal measured after the operator begins a driving operation, and wherein the state-of-attention determination section is configured to determine a state of attention of the operator performing the driving operation based on the calculated eye fixation related potential and the adjusted determination criterion; and an output section for acting to call attention of the operator based on a result of determination, wherein the state-of-attention determination section is configured to determine the state of attention of the operator by comparing an amplitude value of a lambda response of the arithmetic-meaned eye fixation related potential against a determination threshold which is the determination criterion.