This study, using microdata from the Basic Survey of Japanese Business Structure and Activities, empirically examines the relationship among innovation, labour hoarding and employment growth at Japanese firms from 1991 to 2010. The main findings are as follows. First, the labour force of many firms in Japan is above the optimal level (labour hoarding). Second, labour hoarding is more serious among larger firms. Third, firms do not adjust employment instantaneously; if they have surplus labour in the current period, they will gradually reduce it. This is consistent with the theoretical model on employment adjustment that we propose. Fourth, all else being equal, firms’ conducting R&D are more likely to increase employment. Fifth, while we observe a negative correlation between firms’ total factor productivity growth and employment, total factor productivity growth through innovation has a positive impact on employment. Finally, in the manufacturing sector, product innovation, which we proxy by R&D expenditure, has a positive impact on employment, while in the nonmanufacturing sector, process innovation, which we proxy by capital investment, has a positive effect on employment.