• The Mathematics Educator (TME)
• Preuve-Proof-Preuba 
• European Research in Mathematics Education (book)
• Chreods 
• Philosophy of Mathematics Education Journal (PMEJ)
• Journal For Research In Mathematics Education (JRME) (subscribers only)
• Linear Algebra and its Applications (LAE)
• Adults Learning Maths (ALM) 
• DeLiberations
• MAA Online's Teaching and Learning Section

• Educational Studies in Mathematics (ESM) 
• For the Learning of Mathematics (FLM)
• Journal of Mathematical Behavior (JMB)
• Journal For Research In Mathematics Education (JRME)
• International Journal of Computers for Mathematical Learning  (IJCML)
• International Journal of Computer Algebra in Mathematics Education (IJCAME)
• Science & Education (S&E)
• Mathematics Teaching (MT-AMT)
• Micromath 
• Mathematics Teacher (MT-NCTM)
• Mathematics Teaching in the Middle School (MTMS)
• Teaching Children Mathematics (TCM)

See also Peter Gates' list of Maths Ed Journals.