To provide a motor controller and a motor control method that prevent a current from flowing into a failed switching element concentrically.

The motor controller includes a plurality of pairs of switching elements Q1-Q6 connected to both ends of a DC power source through a power supply line, a rectifier element connected parallel to each of the plurality of pairs of switching elements Q1-Q6, a polyphase motor connected to a connection point of the plurality of pairs of switching elements, short-circuit failure detecting means which detects a short-circuit failure of the switching element, phase voltage detecting means which detects a phase voltage of each phase of the polyphase motor, and control means which controls on/off of the switching elements Q1-Q6 for converting a DC power of the DC power source to an AC power. When the short-circuit failure detecting means detects a short-circuit failure of the switching elements Q1-Q6, the control means controls the switching elements Q1-Q6 of a second phase according to a first phase voltage of a first phase including the switching elements Q1-Q6 of short-circuit failure and a second phase voltage of the second phase which is different from the first phase.