A one-dimensional quantum crystal with a point defect (vacancy, impurity, implanted interstitial atom, etc.) is considered. It is shown that the presence of such a defect causes a deformation around it. The defect and the deformation formed are strongly bound. However, they can move together. Owing to quantum-mechanical transition probability they turn into a quasiparticle called 'the solitary defecton' (or 'the soliton'). Such a quasiparticle propagates along the crystal with a constant velocity without changing its shape.