A numerical controller determines a consumption factor representing the degree to which a tool included in a machine tool consumes the life in association with machining conditions, and calculates a tool life (accumulated consumption life) consumed before each block based on the determined consumption factor and a tool usage for each block. If a command of a block read from a machining program is a tool change command, a tool having a tool life not ending before the next tool change command is selected among tools based on the accumulated consumption life.