Provided is a highly safe and effective compound represented by the following general formula (1) or a salt thereof which acts on tubulin and has an anticancer effect, wherein Ar represents an aryl group or a heteroaryl group； Z 1 , Z 2 , Z 3 , and Z 4 each independently represent CH, a nitrogen atom, an oxygen atom, or a sulfur atom； R 1 represents a hydrogen atom, a halogen atom, an alkyl group, or the like； R 2 and R 3 are the same or different and each represent a hydrogen atom, a halogen atom, a carboxyl group, or the like； n units of R 4 are the same or different and each represent a hydrogen atom, an alkyl group, or the like； and n represents a number of 0 to 4.
