Sarcopenia, or age-related muscle loss, is a common comorbidity in patients with chronic obstructive pulmonary disease (COPD) with multiple contributing factors. We hypothesized that the presence of sarcopenia can be estimated using quantitative computed tomography-based parameters in patients with COPD. We retrospectively evaluated 38 elderly (≥65 years) men with COPD for pooled data, including hand grip strength and gait speed. Sarcopenia was diagnosed based on the updated 2019 criteria set by the Asian Working Group for Sarcopenia. Cross-sectional area of the erector spinae muscle (ESM) and pectoralis muscle (PM) were quantitatively evaluated and adjusted by height (ESM-I, and PM-I). Sarcopenia was diagnosed in 11 (29%) patients. The mean ESM-I and PM-I were 11.0 and 9.5 cm2/m2, respectively, and significantly correlated with height-adjusted appendicular skeletal muscle mass. The optimal cutoff ESM-I for the presence of sarcopenia was 9.41 cm2/m2. ESM loss helped estimate sarcopenia in patients with COPD.