A new pentacene dendrimer was synthesized in 81% yield through the aromatization of a dihydropentacene derivative having benzyl ether dendrons at the C2, C3, C9, and C10 positions. The dendrimer is very soluble in various organic solvents such as toluene, benzene, chloroform, dichloromethane, acetone, and ethyl acetate. The half-life of the dendrimer reaches 22.4 min upon photoirradiation in air. Interestingly, regiospecific [4 + 2] cycloaddition reactions proceeded at the central ring of the pentacene.