“…Some results on this operator can be found for example in (Adams, 1975), (Nakai, 1994), (Kurata, et al, 2002) and (Eridani, et al, 2014). Other results on the different version of fractional integral operator can be viewed in (Sawano and Shimamura, 2013) and (Sihwaningrum and Sawano, 2013). Meanwhile, the fractional integral operator (equation 1) has been proved to satisfy the weak-(1, q) inequality (where 1 ≤ q < ∞) in Lebesgue spaces (García-Cuerva and Gatto, 2004), in Morrey spaces (Sihwaningrum, 2016a) and in generalized Morrey spaces (Sihwaningrum, et al, 2015).…”