We analyzed using Workplace Panel Survey (WPS) data on the impact of labor flexibility on innovation performance at the firm level. Verifying the impact of labor flexibility on innovation performance, the higher the flexibility of employment adjustment, the higher the level of employee-led innovation is than the industry average, and the higher the flexibility of contingent employment, the higher the probability to stay in copycat-level workplace innovation. In addition, the higher the wage flexibility and functional flexibility of a firm, the higher the probability that the level of employee-led innovation and product/service innovation will exceed the industry average, and the higher the level of workplace innovation. In addition, analysis of the buffering effects of interaction with employment flexibility, the negative impact of the flexibility of contingent employment on workplace innovation has been shown to buffer or convert by wage flexibility and functional flexibility. The findings suggest that, unlike wage flexibility and functional flexibility, employment flexibility does not positively impact innovation performance, so a detailed review of employment flexibility implementation is needed unless very reasonable reasons are involved. And it can be emphasized that mixed flexibility strategies should be used to secure long-term competitiveness from a Paradox perspective.