Higher maize plant density represents a possible tool for biomass yield improvement but the effect on biogas production and quality has not been intensively investigated so far. The aim of the study was to compare two different plant densities (90 000 and 130 000 plants ha−1) and their effects on yield and biogas production. Experiments were carried out at two sites in Central Bohemia in 2014 and 2015. Specific biogas yield of maize ears and stover was evaluated in batch tests. In both years, there were significantly higher dry matter yield, volatile solids (VS) degradation, and methane content in biogas from ears in comparison with stover. Stover produced on average 90% of biogas per weight unit (625–719 L kg−1 VS) compared to ears (721–801 L kg−1 VS) depending on locality and year. During the batch tests, ears produced more biogas than stover with the exception of the period from the 4th to 11th day when specific biogas yield of stover was higher. Biogas hectare yield of ears (5039–8962 m3 ha−1) was 1.3–1.8 times higher than biogas hectare yield of stover (3943–4865 m3 ha−1). The influence of plant density on dry matter yield and biogas hectare yield was not significant, but higher plant density supported faster dynamics of specific biogas yield of ears in both years and higher volatile solids degradation of ears in 2014.