In this paper, the shock waves induced by a nanosecond pulsed laser in copper target are studied and the relative pressures of shock waves are measured by using the piezoelectric polyvinylidene fluoride piezoelectric sensors. The evolutions of the relative pressures of shock waves with laser pulse energy and target thickness are discussed. Experimental results show that the pressure of shock wave is 2.1 MPa when the nanosecond pulsed laser with an energy of 500 mJ irradiates on a 2 mm thick copper target. When the laser energy increases from 200 to 500 mJ, the pressures of shock wave can increase 162% and 231%, with the target thickness values being 2 and 4 mm respectively. But when the thickness of the copper target increases from 2 to 6 mm, the pressures of shock waves with laser pulse energies of 400 and 500 mJ are reduced by 32% and 49%, respectively.