A numerical controller for controlling a five-axis machining apparatus, in which a tool orientation command is corrected to thereby attain a smooth machined surface and a shortened machining time. The numerical controller includes command reading means that successively reads a tool orientation command, tool orientation command correcting means that corrects the tool orientation command so that a ratio between each rotary axis motion amount and a linear axis motion amount is constant in each block, interpolation means that determines respective axis positions at every interpolation period based on the tool orientation command corrected by the tool orientation command correcting means, a motion path command, and a relative motion velocity command such that a tool end point moves along a commanded motion path at a commanded relative motion velocity, and means that drives respective axis motors such that respective axis positions determined by the interpolation means are reached.