A brushless-motor drive apparatus comprising: a drive circuit of a brushless motor having a plurality of parallel-connected arms including switching element pairs formed of first switching elements (5uH, 5vH, 5wH) disposed on a power supply side and second switching elements (5uL, 5vL, 5wL) disposed on a ground side connected in series in each pair; current detecting means (6u, 6v, 6w) for detecting currents flowing through armature windings of the brushless motor during periods when the switching elements of the drive circuit are ON; motor position detecting means for detecting an angle of a magnetic pole position of the brushless motor; calculation processing means for comparing a target current value to drive the brushless motor and detection current values detected by the current detecting means, and calculating voltage command values to be applied to the armature windings of the brushless motor on the basis of deviations; and PWM driving means for controlling ON/OFF of the switching elements of the drive circuit by generating drive signals on the basis of the voltage command values from the calculation processing means, wherein: the calculation processing means further includes current-detection possibility evaluating means for evaluating whether or not the currents flowing through the armature windings of respective phases of the brushless motor can be detected according to operating states of the switching elements of the respective phases of the drive circuit; characterized in that when the current-detection possibility evaluating means evaluates that the currents cannot be detected, the calculation processing means obtains the voltage command values by making a comparison with the target current value using detection current values detected before and continues a motor drive; and when a state in which currents cannot be detected continues for a predetermined time in the current-detection possibility evaluating means, the PWM driving means outputs a drive signal that extends an ON period of the second switching element of a phase in which a current cannot be detected, so that a phase current can be detected. a drive circuit of a brushless motor having a plurality of parallel-connected arms including switching element pairs formed of first switching elements (5uH, 5vH, 5wH) disposed on a power supply side and second switching elements (5uL, 5vL, 5wL) disposed on a ground side connected in series in each pair; current detecting means (6u, 6v, 6w) for detecting currents flowing through armature windings of the brushless motor during periods when the switching elements of the drive circuit are ON; motor position detecting means for detecting an angle of a magnetic pole position of the brushless motor; calculation processing means for comparing a target current value to drive the brushless motor and detection current values detected by the current detecting means, and calculating voltage command values to be applied to the armature windings of the brushless motor on the basis of deviations; and PWM driving means for controlling ON/OFF of the switching elements of the drive circuit by generating drive signals on the basis of the voltage command values from the calculation processing means, wherein: the calculation processing means further includes current-detection possibility evaluating means for evaluating whether or not the currents flowing through the armature windings of respective phases of the brushless motor can be detected according to operating states of the switching elements of the respective phases of the drive circuit; characterized in that when the current-detection possibility evaluating means evaluates that the currents cannot be detected, the calculation processing means obtains the voltage command values by making a comparison with the target current value using detection current values detected before and continues a motor drive; and when a state in which currents cannot be detected continues for a predetermined time in the current-detection possibility evaluating means, the PWM driving means outputs a drive signal that extends an ON period of the second switching element of a phase in which a current cannot be detected, so that a phase current can be detected. the calculation processing means further includes current-detection possibility evaluating means for evaluating whether or not the currents flowing through the armature windings of respective phases of the brushless motor can be detected according to operating states of the switching elements of the respective phases of the drive circuit; characterized in that when the current-detection possibility evaluating means evaluates that the currents cannot be detected, the calculation processing means obtains the voltage command values by making a comparison with the target current value using detection current values detected before and continues a motor drive; and when a state in which currents cannot be detected continues for a predetermined time in the current-detection possibility evaluating means, the PWM driving means outputs a drive signal that extends an ON period of the second switching element of a phase in which a current cannot be detected, so that a phase current can be detected.