We obtain the Hyers-Ulam stability and modified Hyers-Ulam stability for the equations of the form g ( x + p ) = φ ( x ) g ( x ) in the following settings: | g ( x + p ) − φ ( x ) g ( x ) | ≤ δ , | g ( x + p ) − φ ( x ) g ( x ) | ≤ ϕ ( x ) , | ( g ( x + p ) / φ ( x ) g ( x ) ) − 1 | ≤ ψ ( x ) . As a consequence we obtain the stability theorems for the gamma functional equation.