The aim of this paper is to empirically analyse the mediator effect of innovative work behaviour between a HPWS and product innovation. Using PLS, this paper tests in a sample of 225 Spanish manufacture companies the relationships among HRM, IWB and product innovations. Our results provide strong evidence about the effect of the system of HRM practices on innovative work behaviour and new products. Specially, this paper has found support for the mediation. Although the study counts with the limitations of cross-sectional studies, it provides support for the necessity to develop innovative behaviours that allow the creation of innovations. For this purpose, companies should develop a set of HRM practices that promote these behaviours. This paper show what kind of HRM practices and behaviour should be promote in those companies that follow innovative strategies for obtaining radical and original innovations. The most relevant finding of the paper is the evidence about the mediation effect of IWB on the relationship between HRM practices and innovation. Although literature has demanded attention to this point, only few studies have been focused empirically on this topic. This paper attends to this gap and supports the necessity of paying more attention to IWB in innovative companies.