  The author \mbox{(Appl. Math. Comput. 218(3):860-865, 2011)} introduced a new
fractional integral operator given by, \[ \big({}^\rho
\mathcal{I}^\alpha_{a+}f\big)(x) = \frac{\rho^{1- \alpha }}{\Gamma({\alpha})}
\int^x_a \frac{\tau^{\rho-1} f(\tau) }{(x^\rho - \tau^\rho)^{1-\alpha}}\,
d\tau, \] which generalizes the well-known Riemann-Liouville and the Hadamard
fractional integrals. In this paper we present a new fractional derivative
which generalizes the familiar Riemann-Liouville and the Hadamard fractional
derivatives to a single form. We also obtain two representations of the
generalized derivative in question. An example is given to illustrate the
results.
