  We discuss possibility of the existence of tetraquark states made of four
quarks in the string (flux tube) model. The new particle is composed of a
diquark and an anti-diquark which are connected by a color flux. It is shown
that the vibrational and rotational excited states of the string explain some
non-$\bar{q}q$ mesons observed experimentally. Moreover we discuss the decay
widths of such tetraquarks with the use of the Schwinger mechanism.
