Objective: This cross-sectional study was conducted to assess the association between serum albumin concentration (SAC) and microvascular complications in hypertensive patients complicated by type 2 diabetes mellitus (T2DM). Design and Method: Four hundred and ninety five hypertensive patients (331 men) with T2DM were investigated. SAC was compared between patients with and without microvascular complications (retinopathy, nephropathy, and neuropathy). Then, logistic regression analyses were performed to examine the effects of various factors on microvascular diseases, and the following factors were considered as independent variables: SAC, gender, age, duration of diabetes, body mass index (BMI), systolic blood pressure (SBP), HbA1c, eGFR, LDL-cholesterol, and triglyceride. Results: The age, duration of diabetes, BMI, HbA1c, and SAC of 495 patients were 65.7 ± 13.2 years, 14.7 ± 10.8 years, 26.3 ± 6.5 kg/m2, 8.9 ± 2.0 %, and 3.8 ± 0.6 g/dl. Two hundred and fifteen (43%) patients had retinopathy, 284 (57%) had nephropathy, and 345 (70%) had neuropathy. SAC was significantly lower in patients with retinopathy (3.55 ± 0.67 vs. 3.92 ± 0.58 g/dl, p < 0.01), nephropathy (3.53 ± 0.66 vs. 4.04 ± 0.50 g/dl, p < 0.01), and neuropathy (3.68 ± 0.65 vs. 3.95 ± 0.61 g/dl, p < 0.01) than in those without complications. The results of logistic regression analyses were as follows. SAC, age, duration of DM, SBP, HbA1c, and eGFR were independent explanatory factors for retinopathy. SAC, duration of DM, and SBP were independent factors for nephropathy. SAC, duration of DM, and SBP were independent factors for neuropathy. Conclusions: In hypertensive patients with T2DM, SAC was lower in those with retinopathy, nephropathy, and neuropathy. The results of multivariate analyses showed that SAC was a common explanatory factor for three microvascular complications. Therefore, low SAC in hypertensive and diabetic patients might have pathophysiological significance in the onset of microvascular complications.