A motor control device, comprising: control signal output means for outputting motor control signals; and a driving circuit that outputs three-phase driving electric power based on the motor control signals, wherein the driving circuit is formed by connecting switching arms, formed by serially connecting pairs of switching elements ( 18a to 18f) that are turned on or off based on the motor control signals, in correspondence with respective phases, in parallel with one another, the switching arms respectively have current sensors ( 21u, 21v, 21w) for detecting phase current values of the respective phases corresponding to the switching arms at low potential sides thereof, the control signal output means generates the motor control signals based on phase current values of the respective phases, detected at a timing at which all low potential side switching elements ( 18d, 18e, 18f) of the respective switching arms are turned ON, and when an ON time of any one of the low potential side switching elements ( 18d, 18e, 18f) is shorter than a detection time of the current value, the control signal output means estimates a phase current value of a current undetectable phase based on phase current values of two phases other than the current undetectable phase corresponding to the said switching element, characterized in that at the time of current detection of the two phases, the motor control signals for maintaining switching states of the switching arm corresponding to the current undetectable phase are output such that the high potential side switching element is kept ON and the low potential side switching element is kept OFF. control signal output means for outputting motor control signals; and a driving circuit that outputs three-phase driving electric power based on the motor control signals, wherein the driving circuit is formed by connecting switching arms, formed by serially connecting pairs of switching elements ( 18a to 18f) that are turned on or off based on the motor control signals, in correspondence with respective phases, in parallel with one another, the switching arms respectively have current sensors ( 21u, 21v, 21w) for detecting phase current values of the respective phases corresponding to the switching arms at low potential sides thereof, the control signal output means generates the motor control signals based on phase current values of the respective phases, detected at a timing at which all low potential side switching elements ( 18d, 18e, 18f) of the respective switching arms are turned ON, and when an ON time of any one of the low potential side switching elements ( 18d, 18e, 18f) is shorter than a detection time of the current value, the control signal output means estimates a phase current value of a current undetectable phase based on phase current values of two phases other than the current undetectable phase corresponding to the said switching element, characterized in that at the time of current detection of the two phases, the motor control signals for maintaining switching states of the switching arm corresponding to the current undetectable phase are output such that the high potential side switching element is kept ON and the low potential side switching element is kept OFF.