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 Z1, Z2, Z3, and Z4 each independently represent CH, a nitrogen atom, an oxygen atom, or a sulfur atom R1 represents a hydrogen atom, a halogen atom, an alkyl group, or the like R2 and R3 are the same or different and each represent a hydrogen atom, a halogen atom, a carboxyl group, or the like n units of R4 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.
