74hc595 with 16f877a interfacing problem

74hc595 without connecting the pic also, the output leds to the 595 is always on, the connection diagram is as below
when i touch the pins of 595, the output pins on and off irregularly

what canbe the problem?

connection diagram as below

You found out why you cannot have floating inputs on a CMOS circuit. That is an undefined state for the inputs and, due to their high impedance, can float to any voltage. Touching the pins will add or subtract charge on the gates, randomly changing their state.
All inputs must either be tied to logic high or logic low, even unused ones.

I tied the QH', the only unconnected pin to gnd, now also , same result

Did you reset the chip after power is applied?
A chip will come up in a random configuration upon power up.
How are the LEDs connected?