Let \(-1/2<a<0\) be a fixed real number and let \(\begin{aligned} \Delta _{a}(x)= \mathop {\sum \nolimits '}_{n \le x} \sigma _a(n)-\zeta (1-a)x-\frac{\zeta (1+a)}{1+a}x^{1+a}+\frac{1}{2}\zeta (-a). \end{aligned}\) In this paper, we investigate the higher-power moments of \(\Delta _a(x)\) and give the corresponding asymptotic formula for the integral \(\int _{1}^{T}\Delta _a^k(x) \, \textrm{d}x\) , which constitutes an improvement upon the previous result of Zhai (Acta Arith 112(4): 367–395, 2004) for \(k=3,4,5\) and an enlargement of the upper bound of k to 7.