The main motivation for this article is to construct a model that induces reserve army effect within a Kaleckian model of income distribution and effective demand. Using this model, we investigate the relationship between the wage pressure and employment not only in the short run but also in the long run. The one of the features of the Kaleckian model is that the real wage rate is exogenous parameter by monopoly power of market. So the Kaleckian model excludes the reserve army effect. But much paper insists wage rate is affected by not only monopoly power but also imperfect labor market, especially employment rate and wage pressure of labor union. Some papers try to induce the imperfect labor market within the Kaleckian model. Following previous works (Stockhammer (2004), Dutt (1992)), it is difficult to develop the Kaleckian model with the reserve army effect in the long run because of the indeterminacy problem, in the sense that the long-run equilibrium point diverges from the steady state. The novelty of this paper is that we introduce not only cost minimization but also an increasing-return-to-scale production function into the model. To satisfy the stability condition, we need both increasing return to scale and the scale effect of the product function is strictly above unity or the slope of the wage-setting curve is small. Hence, the relationship between the degree of increasing return to scale, and the slope of the wage-setting curve is important to satisfy the stability condition. If the condition is fulfilled, an increase in the capital stock leads to excess supply in the product market, and a decrease in employment. This process will go on until the labor-capital ratio is equal to the desired labor-capital ratio. Another result of this paper is that an increase in the wage pressure increases employment in the long run compared to the initial level.